Operation Sea Lion: The German Invasion Plan of Britain

Introduction and Background

On June 14, 1940 speaking in the House of Commons the then British Prime Minister Sir Winston Churchill announced that “The Battle of France is over, I expect that the Battle of Britain is about to begin”. (1). This statement of Sir Winston Churchill was a virtual reflection of the situation at that period during the Second World war. The Second World War had opened in September 1939 with the invasion of Poland by Germany. The vigorous German military might in the short period of nine months had established its hegemony over practically the whole of Western Europe with the fall of France, and the quick evacuation of the British Expeditionary Force (BEF) from Dunkirk to the shores of Britain. Only Britain stood between Germany and its total hegemony over Western Europe. (2)

There was very limited confidence in the ability of Britain to withstand the expected invasion of Britain by Germany around the world, and even in the eyes of the United States of America. The American ambassador at that time to the Court of St. James was Joseph Kennedy, whose son was destined to become the President of the United States of America at a future date. In Joseph Kennedy’s evaluation that was sent to Washington, he expressed the opinion that Britain was not in a position to defend itself for long against a sustained German invasion. (3).

The invasion of Britain was a natural extension in Hitler’s plans that transcended beyond the mere subjugation of Western Europe. Hitler had already targeted Russia in the east in his expansion plans. Once Britain had been brought under the heel of the German forces, the invasion of Russia would become easier. Domination of Britain was essential to this plan of Hitler. Yet, Hitler was not averse to a peace settlement with Britain, for his greater ire was against Russia, and he held the desire for a quick destruction of Russia, which would be enabled through a peace settlement on his terms with Britain. (4)

Encouraged by an apparent willingness of Britain, based on misplaced belief, Hitler in his July 19, 1940 speech gave reality to this intent. However, Hitler did not receive the expected positive response from Britain, and he had to fall back on the already prepared plans for the actual invasion of Britain, as the means to remove this thorn that remained for him in Western Europe. Operation Sea Lion was the name given to the German plan for the invasion of Britain using the amphibious route across the English Channel. (5).

The prophecy of the inability of Britain to successfully ward off any invasion by Germany was essentially grounded on the ease with which the German Army had made mincemeat of the large BEF in Europe, and the mauled state of the British Army. However, the success of Operation Sea Lion hinged on the German capability to hold the space across the English Channel successfully against any interdiction by the Royal Air Force (RAF) and the Royal Navy (RN) for an amphibious landing of the Germany Army on English shores. The RAF and the RN were the recipients of a larger proportion of defense spending in Britain prior to the start of the war, and hence were in a much better prepared state to take on what the Luftwaffe and Kriegsmarine could throw at them. (6)

Operation Sea Lion could be stated to have officially started on July 10, 1940, even before Hitler’s expression for a negotiated settlement on July 19, 1940. It lasted for about three months. Operation Sea Lion ceased to exist as a German invasion plan of Britain on October 12, 1940. It was a brief life span for a plan that was expected to bring Britain to its knees. (7).

The RAF was not the sole factor that led to the cancellation of the doomed Operation Sea Lion, the German plan to invade Great Britain during the Second World War

Factors that Contributed to the Cancellation of Operation Sea Lion

Operation Sea Lion

Operation Sea Lion was the code name given for the German invasion plan of Britain. Hitler had hoped that with the fall of France, Britain would be eager for a compromise with Germany, allowing him to turn east to settle scores with Russia. In keeping with this hope, diplomatic efforts were initiated through the governments of Sweden, Switzerland, and the Vatican. These efforts for a negotiated settlement with Britain did not bear fruit. In July 19, 1940, Hitler in his announcement to the Reich Chancellery put forth to Britain his final peace proposal, in which Germany would desist from invading England, and in return there would be no interference from Britain to whatever Germany chose to do on mainland Europe. (8). The turning down of this peace proposal by Britain was not a surprise, as the determination of Britain to go down fighting, if push came to shove at this juncture, could be seen in these words of Winston Churchill, “If the long history of our island is to come to an end, then it shall only end when every last one of us is beaten to the ground and lies choking in his blood”. (9).

Germany had prepared itself in case Britain refused to comply with its peace proposals. By the end of June 1940, Lieutenant General Jodl had submitted to Hitler a report giving the possible attack options that lay before Germany in the face of a British refusal of the peace overtures. The German High Command of the Armed Forces Ober Kommando der Wermacht (OKW) on July 2 1940, followed up this action by calling on the Wermacht (army) , Kriegsmarine (navy), and Luftwaffe (air force) to begin preparing for the invasion of Britain. The invasion plan was called Seelowe or Sea Lion, and in simple terms called for the Luftwaffe to dominate the skies over the English Channel and Britain, while the Kriegsmarine under the cover of this air domination, controlled the waters of the English Channel to transport the Wermacht from select take off points in Europe to the selected landing points on English soil. On July 16, 1940, three days prior to his final peace offering to Britain, Hitler gave the green signal for starting the preparations of this landing operation against Britain. Mid-August was the selected target date for completion of the preparedness of Operation Sea Lion. (10).

The seeds in the planning of Operation Sea Lion started even before the Battle for France. Captain Hans Jurgen Reinicke of the Kriegsmarine had in detail worked out the enormous difficulties involved in any invasion plan of Britain, using the available German coastline. In November 1939, when the plans for the Battle of France using Netherlands as the access point to France were under consideration by the German High Command, Admiral Erich Raeder of the German Navy brought up the importance of invading Britain, with a suggestion for using the shores of France as a launch pad, once France was taken, rather than using the German coastline, based on the difficulties pointed out by Captain Hans Reinicke. This suggestion was not found interesting to the Luftwaffe Commander Reich Marshall Hermann Goering, but it made sense to the Army High Command, who gave it due consideration. (11).

Operation Sea Lion as planned by OKW consisted of the landing of the German Army on a wide sector of the South-Eastern coast of Britain. Army Group A under Field Marshal von Rundstedt had led the successful German push in the Battle of France, and this army group was again selected to lead Operation Sea Lion. Six divisions of the Sixteenth Army of Army Group A were to set off from Pas-de-Calais and land on beaches between Ramsgate and Bexhill in South Eastern Britain. Another four divisions of the Ninth Army of Army Group A would use a number of kick-off ports in the area between Caen and Dieppe of the Havre region to reach their designated landing zones across the English Channel on the southern English coastline in an area that ranged from Brighton to Portsmouth. This crossing of Army Group A would be augmented by elements of Field Marshall Block’s Army Group B. Three divisions of Army Group B would use the Cotentin peninsula at Cherbourg as a launching pad to get across the English Channel, and land on either side of Lyme bay on the South western coastline of Britain. (12)

These thirteen divisions of almost 90,000 men would constitute the first wave of German forces across the English Channel. The logistics involved in the first wave alone was massive. Moving the first wave and its equipment across the English Channel would require marshalling a huge fleet of sea going vessels. It was estimated that 155 ships totaling a tonnage of 700,000 tons would be required. In addition, 3000 smaller vessels in the form of barges, tugs, and motorboats would also be required in this massive movement of German forces across the English Channel. (13).

The first wave was to be followed on the second day of Operation Sea Lion by a second wave that would consist of moving six armored divisions and three motorized divisions across the English Channel. On the third day of Operation Sea Lion the German forces on English soil were to be augmented by a further 17 infantry divisions in a third wave across the English Channel. In this manner, Operation Sea Lion envisaged the presence of 39 army divisions of different types consisting of 260.000 men and their equipment available for the invasion of England on English soil. (14)

The OKW planners of Operation Sea Lion believed that the time period between the start of Operation Sea Lion and the end of the Battle for Britain would take approximately four weeks. Mid August 1940 was thus chosen as the launch date for Operation Sea Lion to meet Hitler’s requirement of the subjugation of Britain by September 15, 1940, to enable him to turn eastwards and invade Russia, which was a greater priority for him. The surmise of the OKW planners of Sea Lion was that the 39 army divisions transported across the English Channel by the sea route, coupled with the two paratroop divisions that would be airdropped over Britain, would be more than enough to defeat the resistance of the estimated 29 British Army divisions over this span of time. Operation Sea Lion was thus a massive sea borne operation to be taken up at short notice, supported by domination of the skies over the English Channel, and if not the whole of British skies, at least the air space over southern Britain by the Luftwaffe, and completed within a limited time frame of four weeks from its launch in Mid August 1940. These critical elements in the plan of Operation Sea Lion would in combination result in the cancellation of grandiose Operation Sea Lion by October 12, 1940. (15).

Critical Success Factors Involved in Operation Sea Lion

In military strategic planning parlance the focus of any strategic level or operational planning should be on the centers of gravity of the opposing forces. Military doctrine defines centers of gravity as “Those characteristics, capabilities, or localities from which a military force derives its freedom of action, physical strength, or will to fight”. (16). Efficient analysis of the centers of gravity in military planning provides clear insight into those areas of enemy strengths that have to be concentrated on for either elimination or containment without wasting the available military resources on unwanted areas to win a particular battle. (17).

To better understand what centers gravity really imply let us draw an analogy from the field of business, and the battles that occur to gain competitive edges in market places. Critical success factors for any business enterprise may be defined as “the limited number of areas in which results, if they are satisfactory, will ensure successful competitive performance”. (18). In essence, critical success factors make up the specific areas in which a business enterprise needs to concentrates its efforts to win the competitive battles it fights in the business world. (19). Translating critical success factors in the business world into the centers of gravity approach in military strategic planning shows those areas where success is essential for the positive outcome of a military operation.

Captain Hans Jurgen Reinicke had identified several critical success factors that were essential to meeting the objective of Operation Sea Lion, namely the invasion of Britain. These critical success factors are:

• Destruction of the Royal Air Force to ensure air dominance over the English Channel, coastline and English skies.
• Putting together the huge fleet of transport ships, barges, tugs, and motor boats that would be required to ferry the men, materials, tanks, and other heavy equipment of the German Army across the English Channel. This would also include locating suitable marshalling ports on the French coastline, protecting these marshalling from prying eyes, and finding appropriate landing sites on the rugged English coastline for the landings to occur.
• Destroying the ability of the Royal Navy surface vessels to interdict the marshalling of the transport fleet, and the control of the waters of the English Channel during the crossing of the invasion fleet.
• Elimination of any possible threat from Royal Navy submarines to the invasion fleet.
• Removal of any mines in the path of the invasion fleet, through a massive de-mining operation. (20).

The critical success factors clearly demonstrate that Operation Sea Lion required a joint effort on the part of several elements of the German fighting forces, and was not entirely concentrated on the domination of the Luftwaffe over the RAF, which in essence means that success of the RAF in thwarting the Luftwaffe designs of air supremacy was not the sole factor, as failure in any of the other critical success factors of Operation Sea Lion would lead to its cancellation.

Failure to Prevent the Evacuation of the BEF from Dunkirk

On May 23, 1940 the defeated BEF and elements of the French Army were enclosed in the French town of Dunkirk and the beaches adjacent to the town. This entire force consisted of 337,000 soldiers of whom approximately 226,000 were the remnants of the BEF and the remaining French soldiers. Encircled on land by superior German armed forces and with their backs to the sea, this force was ripe for destruction or capture by the German Army. Yet, this did happen, and instead the almost entire force was evacuated back to Britain. (21).

The reason for the German Army not seizing the opportunity is clear in that an order was received from Hitler to desist from destroying or capturing the Allied forces, and instead to turn southwards to complete the defeat of the French Army at Somme. What is not clear however, are the reasons behind this decision of Hitler. Many reasons have been put forward, but the most plausible reason appears to be the reluctance of Hitler to really continue fighting with Britain, and instead only wanted Britain to accept its superior role in mainland Europe. This explanation appears more plausible when connected to the lack of perseverance in attempting to make Operation Sea Lion a success. Seen from this perspective, it is more likely that Hitler preferred to use the bottling up of the Allied forces at Dunkirk to force Britain to sue for peace. Hitler may have viewed that the capture of such a large British armed force would only make the proud British more defiant and refuse any peace terms. There is a connection in this with Operation Sea Lion. Hitler along with a part of the German High Command, with particular emphasis on the German Navy looked on any invasion plans of Britain as a risky adventure, and hence the greater stress on getting Britain to agree to peace terms suitable to German interests. (22).

Whatever be the reasons the respite gained by the halting of the advance of the German Army on the stranded Allied forces at Dunkirk, permitted their evacuation back to Britain. According to Waller 1996, p.136 “It is clear that the rescue of the expeditionary force, heart of the British Army, permitted the British to fight another day and made a German invasion of the British Isles a more risky proposition from the German point of view”. (23). Thus, the seeds of failure of Operation Sea Lion were sown by not preventing the evacuation of the remnants of the BEF from Dunkirk, and this failure needs to be considered as a factor contributing to the failure of Operation Sea Lion.

The Flaw in the Planned Invasion Front of Operation Sea Lion

Operation Sea Lion was planned in such a way that the invasion force would take the shortest path across the English Channel from France to the shores of Southern Britain. No other alternative route was a part of this planned invasion of Britain. This shortest route across the English Channel from France was considered by Britain as the likely thrust point of any attacking force from France across the English Channel historically. The southern coast of the British Isles was thus the most defended part of Britain. The ports along the coast of Southern Britain were well fortified, and were home to a large part of the fleet of the Royal Navy. With the development of air power as an efficient means of offense and defense, Britain had located most of its airfields and air-control stations for its defensive needs in the southern part of the British Isles. The planned invasion front of Operation Sea Lion was thus against the most fortified areas of Britain. According to the then Prime Minister of Britain Sir Winston Churchill “There was no other part of the Island where we could come into action more quickly or in such great strength with all three Services”. (24).

It was not that the Germans were unaware of the risks of an invasion of the southern coast of Britain from French shores. Hitler had been briefed by Admiral Raeder on the risks involved, and this prompted Hitler to consider Operation Sea Lion as “an exceptionally bold and daring undertaking”, and to announce that “Even if the way is short, this is not just a river crossing, but the crossing of a sea, which is dominated by the enemy. This is not a case of a single-crossing operation as in Norway; operational surprise cannot be expected; a defensively-prepared and utterly determined enemy faces us and dominates the sea area which we must use”. (25).

These words of Hitler encapsulate the perils that were inherent in Operation Sea Lion, and its invasion plans of the most defended shores of the British Isles, and yet no alternative route was chosen. Overcoming the perils inherent in the planned invasion front would require the critical areas of the invasion plan remaining successful, thereby increasing the hesitancy on the part of Germany to undertake Operation Sea Lion. The flaw in the planned invasion front of Operation Sea Lion was another nail in the coffin of the doomed Operation Sea Lion.

The Lack of Cohesion and Commitment for Operation Sea Lion

Operation Sea Lion, though conceived before the fall of France, was not really ensconced as a real invasion plan to defeat Britain. All hopes really hinged on the presumed capitulation of Britain in the perspective of their rapid defeat and the capture of France by Germany. This attitude in Germany is reflected in these words of Admiral Raeder the then German Commander in Chief of the Kriegsmarine “Our mental as well as material preparations before the war had not been aimed at an armed conflict with England”. (26).

The lack of seriousness of the German High Command for Operation Sea Lion even after the German forces had reached the coastline of France can be seen from the lack of initiative on the part of Germany to seize the French naval fleet in the French ports. An integral factor in the success of Operation Sea Lion depended on a strong Kriegsmarine, subduing any interference from the Royal Navy. Yet, Germany made no demands with regard to the powerful French naval fleet in its surrender terms to France, nor did it use its military might to seize the fleet. An excellent opportunity to strengthen the Kriegsmarine was thus allowed to pass by the German High Command. (27).

Hitler had clearly demonstrated hesitance in invading England, and this hesitance has been partially laid on his fears that the operation was fraught with risks. Military intelligence plays a key role in the planning and execution of large scale military operations. In this context it would be interesting to note the position of Admiral Canaris the head of German Military Intelligence (Abwehr). Admiral Canaris was a strong opponent to any invasion of Britain, and it is strongly believed that acting behind the scenes, it was Admiral Canaris that raised doubts in the mind of Hitler on the advisability of going ahead with Operation Sea Lion. Abwehr agents in Britain were ill-trained and ineffective in gathering reliable military intelligence. Admiral Canaris took no action to improve the quality of the agents, nor evaluate the quality of the intelligence. For example intelligence input from Abwehr agents put the British Army strength at 37 divisions, when in actuality there were only 29 divisions. This added assessment of the British army strength would only increase the cautious approach of Germany to Operation Sea Lion. The German Naval intelligence had proved to be more effective through the breaking of the British Cipher code, but then it was Admiral Canaris who had the ear of Hitler. (28)

Even when Hitler ordered that preparations be put in place for Operation Sea Lion, serious differences of opinion cropped up between the Kriegsmarine, responsible for the transportation of the invasion army and OKW. In essence their differences were on account of the wariness each experienced due to the weaknesses that both sides felt in their capacities to undertake Operation Sea Lion. Resolving these differences consumed a lot of time and hampered the preparations of Operation Sea Lion (29).

The Kriegsmarine had experienced the capability of the Royal Navy in the Battle of Norway in a much narrower sea channel and at a greater distance from their home shores. The losses taken by the Kriegsmarine and the experiences in the Battle of Norway heightened the wariness of the Kriegsmarine towards the Royal Navy, and reduced their willingness to take on greater risks as required by the invasion plans put forth by OKW. The German Army’s wariness stemmed from unease to invade Britain, as they had neither made plans for an invasion of Britain, nor had they trained themselves for such an exercise (30).

While the Kriegsmarine wanted the sea crossing to occur across a narrow front and the landings to occur on a limited width of English, and with the minimal requirement of men and equipment, owing to its limitations in keeping the Royal Navy at bay, and the sea conditions and tide times, the German Army wanted the crossings to be across a wide area, with spread out landing zones to prevent the British Army from squeezing the invading force. In addition, the Kriegsmarine wanted the launch time pushed as late as possible for it to be prepared for the role it had to play in Operation Sea Lion. The Germany Army wanted Operation Sea Lion to be launched early in keeping with Hitler’s cut off date of completing the invasion of Britain by Mid September. These differences were finally resolved by the German Supreme Command only by August 27, 1940, when the German Army was forced to take into consideration, though reluctantly, the apprehensions of the Kriegsmarine on Operation Sea Lion. (31).

As a consequence Operation Sea Lion became a divided operation among the three senior services of Germany. To the German Army their role was limited to assembling and preparing their men and equipment for the sea crossing, and their main task was to begin only after the men and equipment were deposited on British soil. The Royal Navy had the heaviest task of the colossal movement of men and materials across the English Channel. However, both the German Army wanted the Luftwaffe to attain air superiority over the English Channel and the landing zones before the invasion of Britain really took place, thereby reducing the onus of responsibility on the success Operation Sea Lion on their shoulders. This led to the Luftwaffe being made responsible for not only clearing the skies of the RAF, but also the laying of the mine screen to prevent the Royal Navy from interdicting the ships and boats transporting the German Army and their equipment to the shores of Britain. Reich Marshall Goering took on this heavy responsibility with enthusiasm, for he believed that the numeric superiority of the Luftwaffe would allow him to, in a few weeks, defeat the RAF and destroy the airfields in Kent and Sussex, and thereby attain the desired air domination across the English Channel, to successfully lay the mine screen for the safe movement of the invasion fleet. It is this limited perspective of Operation Sea Lion and the role of the Luftwaffe that gives rise to the impression that the RAF was the sole factor in the cancellation of Operation Sea Lion (32).

Records of the German High Command obtained at the conclusion of the Second World War clearly confirm the lack of cohesion and commitment among the three senior services of Germany. Quite often they worked at cross purposes deliberately ignoring the capabilities and limitations of each other, leading to friction. The Kriegsmarine was at the receiving end most of the time. In Germany it was the Army that held the highest prestige, resulting in the Army taking a condescending approach to their naval colleagues. The consequence of this was that the German Army kept making demands that increased the responsibility of the Kriegsmarine beyond their capacities, and it was only through the intervention of Hitler that the Army could be made to take a more sensible approach to the responsibilities of the Kriegsmarine with regard to Operation Sea Lion. A strong impression among historians is that OKW was not keen on placing itself in the hands of the Kriegsmarine, when it considered it as its junior partner in the German scheme of things. (33).

A similar situation arose with the Luftwaffe. Reich Marshall Goering with his soaring ambition, and his belief in the strength of the Luftwaffe believed that Britain could be brought to its knees solely through the efforts of the Luftwaffe. He felt that the Luftwaffe did not need to play any humble role in any combined operations with the other two senior services of Germany. This is reflected in the refusal of the Luftwaffe to be a part of any combined operation for the systematic obliteration of the RAF and Royal Navy across the planned invasion area. The Luftwaffe took a go it alone approach, concentrating on reducing the fighting ability of the RAF, and ignoring the need for reducing the effectiveness of the Royal Navy, and offering air cover for the marshalling of the ships and boats needed to transport the elements of the German Army in Operation Sea Lion. (34)

Role of British Strategic Planning in the Battle of Britain

Strategic planning of the defense off the airspace over the English Channel and the skies over Britain was essentially skewed towards the belief that France would not fall to Germany, and the extended distance that would have to be covered by the Luftwaffe bombers and fighters to reach these airspaces. However, the fall of France and the occupation of Norway exposed areas of Britain hitherto not considered areas threatened by the Luftwaffe, and also the intensity with which the Luftwaffe could come at the air and ground defenses. Alterations in the strategic planning of defending the skies over Britain thus became imperative, and these British countermeasures can be broken down under two heads. The first was the enhancing the strength in the air defense systems with regard to the intensity of the anticipated air attacks and the extended areas that would need protection. The second was strengthening the numbers of aircraft available to the RAF and the associated defenses, again based on the theme of higher intensity and wider scope of air attacks from Germany. In essence, British strategic planning had rightly assumed a greater role for the Luftwaffe in attacks on Britain with the fall of France, and took steps to augment the countermeasures to the maximum possible, in the limited time available to it. (35).

The consequences of these steps can be seen in the strengthening of the air defensive measures in the South-west of Britain, which contained the closest points to the French coast across the English Channel. For example, west and south west of Middle Wallop presented an area with no air fields for fighter aircraft, except for the airfield at Filton. In quick time airfields were created at St. Eval, Exeter, Pembrey, and Warmwell, with plans for additional airfields in the area. This expansion of airfields allowed the number of fighter air squadrons operating out of the area to be increased to seven, in place of the single air squadron that was present there (36).

Parallel to the increasing the facilities and fighter air squadrons in the anticipated theatre of air warfare, the strategic planning of Britain included extension of the Observer Corps and Radio Direction Finding (RDF) stations along the ground to enhance the early warning systems of approaching Luftwaffe planes for better preparedness in repulsing these attacks. In addition, strategic planning went about enhancing the fighter squadron strengths in anticipation of enhanced numbers of enemy aircraft participating in air attacks on Britain. British planners went about the enhancing of the number of air squadrons in a practical manner, based on the ability to produce them, provide trained pilots to man them, and the availability of airfields to house them. Consequently on an immediate basis the fighter air squadron strength was raised by ten squadrons, with a further enhancement of ten squadrons to follow, and the subsequent enhancement of fighter air squadrons to be based on the above mentioned factors. (37).

Planning also took into consideration the requirement for ground air defenses. Anti-aircraft bases were considered necessary for the protection of the air fields and the industrial belts in Britain. Though it would be unrealistic to claim that adequate numbers of AA batteries were made available for the optimum ground air defenses, the number of air batteries available were increased for these purposes, and supported with adequate number of search lights to make them more effective in warding off night attacks. Another key aspect of the planning of the ground defenses lay in the creation of AA Commands adjacent to the Fighter Commands and Observer Corps, which facilitated close liaison between them, which strengthened the functioning of the ground defenses in facing the challenges thrown at them by the Luftwaffe. (38). Thus strategic planning of defenses against the impeding air attacks of the Luftwaffe were well thought out, coordinated, and implemented, such that when the Luftwaffe launched its air attacks on Britain to meet the objectives set for it, prior to the launch of Operation Sea Lord, it found a determined and prepared adversary in the air and ground defenses of Britain, as a result of efficient British strategic planning

The Role of the Radar and Visual Sighting Posts in the Battle of Britain

Radar is the short form for Radio Detecting and Ranging. The period of the Second World War witnessed the rapid development of radar technology independently by both sides of the combatants. However, the key early breakthrough in radar technology goes to the British, with its discovery of the magnetron, which is the device employed to generate radio signals in a radar system. The first significant use of the radar, as a natural extension, was by the British during the Battle of Britain. The radar enabled early detection of the incoming Luftwaffe, to make use of the limited fighter squadrons in an efficient manner that enabled the RAF to win the Battle of Britain. (39).

In early 1930s, the British Air Defense had installed a set of listening posts along the southern coast of England. The purpose of these listening posts was to act as ears for the British Air Defense as an early warning system, so as to enhance the efficiency of the British Air Defense against any attacks originating from the French side of the English Channel. (40).

In 1935, the English physician Watson Watt put forth the proposition that radio waves reflected off aircraft and the reflection could be received and displayed on screens. This feature could be used to develop an early warning system for incoming enemy aircraft, vastly increasing the efficiency of the British Air Defense listening posts. Watson Watt went on to demonstrate in reality what was put forth in theory that led to the gradual augmenting of the British Air Defense listening to posts with radar stations. (41).

From 1936 onwards, and under the leadership of Air Marshall Hugh Dowding, radar systems were finding increasing use in the British Air Defense. The radar systems consisted of the Chain Home radar. Many of these radar systems were located on the southeast coast of Britain, and the German High Command seemed to have been unaware of the numbers of these radar systems deployed on the British southeast coast, and the effectiveness of these ears and eyes of the British Air Defense. The British had found that the radar systems worked best across the flat surfaces of the seas and were less efficient across land, where the land rises acted as deterrents to its effective functioning. Thus the thrust of the deployment of radar systems were across the seas towards France, with maximum deployment in the southeast in the direction of traditional routes of enemy attacks. (42).

In addition to the increasing installation of radar systems, Air Marshall Dowding also developed a large network of visual sighting posts under the Royal Observation Corps (ROC). The equipment at each listening post consisted of an optical sighting device that was mounted on a plinth. The observer at the visual sighting post used this equipment to estimate the direction, range, height, and speed of the incoming enemy aircraft. It was also possible for the observer to identify the type of the incoming enemy aircraft and the number of enemy aircraft involved in the attack. These ROC observation posts were equipped with telephones, and the observed information was passed on by telephone to the designated filter station. The filter station received information from several observation posts. Based on this input the filter stations could then decipher the progress of the incoming enemy attack, the number of attacks involved, and the probable heading of the attack. This information was then passed on to the sector operation centers, where with the help of plotting maps the incoming enemy air attack was clearly defined. This attack information was then used to scramble the necessary number of British fighters into the air from the spread out different airfields to provide the appropriate response to the enemy air attack. This advance warning of impeding enemy attacks, its intensity, and targets also enabled rotation of the British fighter squadrons responding to enemy air attacks, providing time for the pilots to rest and recoup, and the ground crews to provide the required repairs to the aircraft. (43).

In the Battle of Britain, both Germany and Britain expected to lose both aircraft and pilots. The Germans held a 4:1 numeric superiority in aircraft numbers over Britain, and losses could be replaced by drawing strength from the reserve squadrons based in Norway, Denmark, and the Low Countries. Britain could replace its aircraft losses by calling on the existing stock of aircraft held in reserve and aircraft coming out of its production lines. Replacing aircraft thus was not problematic for Britain. However, the problem lay in finding replacements for the pilots lost. Recruiting pilots and adequately training these pilots was time consuming, and so replacing lost pilots was not easy. It is in this perspective that the radar systems and its augmenting ROC visual sighting posts became important to the RAF sustaining its effectiveness in dealing with the Luftwaffe air attacks, for they acted as force multipliers for the RAF, through their early warning of Luftwaffe air attacks, their intensity, and targets. (44).

This force multiplier effect of the radar was aided by the strategy of the Luftwaffe in developing air attacks on Germany. The tactic of the Luftwaffe was to assemble the bombers and fighter escorts over the skies of France before launching attacks across the English Channel on their British targets. Though it was early days in radar technology, and the radar systems were primitive in comparison to modern day radar systems, they were effective enough to detect the large echoes created by the large number of aircraft being assembled over France to provide a sufficiently early warning of the impeding Luftwaffe attack. In the absence of the radar, there would be no early warning to the RAF of an impeding attack. In addition, the RAF would have had to deploy precious resources of men and aircraft on continuous daytime air patrols over the southern coasts of Britain to reduce the unexpectedness of German air attacks, thereby reducing the operational availability of these aircraft in fighting off enemy air attacks. (45).

The radar system though in the primitive stages of technology and the visual sighting posts, employed by the British Air Defense, acted as eyes and ears for the RAF, detecting enemy attack formations as far as over the skies of France, and as they passed over the, providing reliable information on the type of enemy aircraft involved; the intensity of the enemy air attack; and the target of the enemy air attack. In the absence of this information the RAF would have been hard put to mount an effective response to a numerically superior Luftwaffe responsible for these attacks. In addition, by eliminating the need for the RAF to deploy precious resources of fighter aircraft and their pilots on day light surveillance sorties, the radar and the visual observation made these resources available to the RAF to be deployed against enemy air attacks. Furthermore, the advance information provided by the radar system and the visual sighting posts made it possible for the RAF to rotate fighter squadrons responding to the attacks, and thereby provided much needed time for the pilots to rest and recoup and maintenance of the aircraft. It goes without saying that the balance of the Battle of Britain may have tilted in favor of the Luftwaffe in the absence of the radar system and visual sighting posts, thereby allowing the Luftwaffe the desired air domination for the launch of Operation Sea Lion. The RAF was thus assisted by the radar system and visual sighting posts in thwarting the air dominance by the Luftwaffe, and thus was a major factor in the cancellation of Operation Sea Lion.

Deficiencies in the German Aircraft in the Battle of Britain

The Battle of Britain was the air battle between the Luftwaffe and RAF, in which the Luftwaffe attempted to gain air superiority to secure the objectives given by Hitler to the Luftwaffe and the response of the RAF to thwart the attempts of the Luftwaffe. The air campaign of the Luftwaffe was designed around the objectives set out by Hitler on August 1, 1940. These objectives consisted of destroying the fighting capacity of the RAF through the destruction of its aircraft in air or on the ground, along with its ground defenses; subsequent to the defeat of the RAF, attack on the ports through which food supplies were received into England; knocking out the ships of the Royal Navy and the supply merchant vessels; support Operation Sea Lion; and the conduct of terror raids were only to be undertaken on the express approval of Hitler. However, from the perspective of the Luftwaffe High Command the order of the priorities was interpreted as first to attain air superiority; second to support Operation Sea Lion, by reducing the power of the Royal Navy; third to destroy the ports used for receipt of supplies; and finally to conduct terror raids that were duly authorized (46).

The Battle of Britain reflected the attempts of the Luftwaffe to achieve the first two objectives in its interpretation of the objectives set out by Hitler. To attain the objective of air dominance by the Luftwaffe to support Operation Sea Lion, the Luftwaffe would have to launch its attacks against the RAF fighter planes and bombers, airfields, and the aircraft production factories. Though the Luftwaffe enjoyed vast numerical superiority over the RAF, this edge of superiority had been blunted to a certain extent by its losses in the European war theatre, since September 1939. The Luftwaffe had taken several losses in terms of aircraft and pilots during this period. (47).

In addition, operationally the Luftwaffe was more oriented towards support of ground operations, and not for sustained air efforts in terms of carrying out continuous bombing sorties against enemy airfields and industrial areas. The aircraft used by the Luftwaffe were not designed for such operations. Instead in their design parameters, the Luftwaffe aircraft was not efficient in undertaking long range campaigns, but were dependent on quick victorious by the ground forces to provide airfields for the aircraft to operate from close to the battle theatres. The Luftwaffe successes in European war theatre were to a large extent based on the availability of operational facilities for the Luftwaffe closer to the battle theatres. This would be a missing feature in the Battle of Britain. (48)

The bombers at the disposal of the Luftwaffe in the Battle of Britain were in essence designed for such a strategy. The largest bomber available to the Luftwaffe was the Heinkel He-111. This was a twin-engine commercial aircraft converted into undertaking the role of a bomber. Therefore, it lacked the power and speed requirements of bomber, but it could carry a reasonable payload of bombs. Other bombers like the Junkers Ju-88 or the Dornier Do-17 were much faster aircraft, but carried deficiencies of poor bomb payload and insufficient defensive armor. The last bomber available to the Luftwaffe was the Junkers Ju-87. This aircraft was a dive bomber that featured slow speed, short-range, reduced bomb capacity, and very light armor. The Ju-87 was efficient in its role as a ground support bomber, but practically useless in for the strategic-bombing campaign requirements in the Battle of Britain. The bombers thus available to the Luftwaffe for the sustained strategic bombing campaign required to gain air dominance over the RAF were not really suited for the role that they were expected to perform. (49).

Moving on to the fighter aircraft available to the Luftwaffe in the Battle of Britain, the two main fighter aircraft available were the Messerschmitt Bf-109 and the Messerschmitt Bf-110. The Messerschmitt Bf-109 was a commendable fighter aircraft that could match any of the fighter aircraft that the RAF could throw at it. However, it did not have a long range, and thus could provide air cover for bombing raids for only short periods of time, reducing its efficiency in fighter escort duties. Furthermore, with the early warning systems of the British Air Defenses efficiently providing reliable advance information on impending Luftwaffe air attacks, RAF responses to the attacks occurred earlier and more effectively, forcing the Messerschmitt Bf-109 early into protective action, and causing it to withdraw earlier from its escort duties, exposing the vulnerable bombers of the Luftwaffe. The Messerschmitt Bf-110 was a twin-engine aircraft with a much longer range, and thus suited for long range escort duties of bombers. However, it was much slower in acceleration than the Messerschmitt Bf-109, and had a larger turning radius that made it vulnerable to the RAF fighter aircraft. Nevertheless it had an edge over the RAF fighters in terms of heavier armament than the British fighters, and in a dive situation could really deliver a knock out punch to the British fighters. (50).

Based on the features of the escort fighters the Messerschmitt Bf-109 and the Messerschmitt Bf-110, the Luftwaffe planned their fighter escort design. In this design the Messerschmitt Bf-110 would escort the bombers throughout the bombing raids, while the Messerschmitt Bf-109 provided cover to the Messerschmitt Bf-110 from the British fighters, up to the maximum possible within its range capabilities. (51).

This escort design suffered from two deficiencies. The first deficiency was that the British strengths in terms of its airfields, air defenses, industrial belts, and other military production facilities all lay outside the escort range of the Messerschmitt Bf-109. The British fighters could wait outside the escort range of the Messerschmitt Bf-109, and then pounce on the escorting the Messerschmitt Bf-110s and the German bombers to wreck havoc among them, spoiling the bombing raid. The second deficiency with particular reference to Operation Sea Lion was that the British fighter aircraft could remain outside the fighting range of the Messerschmitt Bf-109, to prevent any harm that could be caused by the Messerschmitt Bf-109, and then resume action within its fighting range once Operation Sea Lion was launched. In essence, the only German fighter aircraft that was capable of taking on the British aircraft was the Messerschmitt Bf-109. (52).

Achieving air dominance over the British skies meant that the Messerschmitt Bf-109s destroy as many of the British fighters in the air, and leave the destruction of the air fields and supporting facilities to the German bombers. The British fighters could play hide and seek with the Messerschmitt Bf-109s, and pounce on the bombers to destroy them, reducing the possibility of the Luftwaffe achieving the desired air dominance for Operational Sea Lion. Thus, the deficiencies in the design features of the German fighters contributed to the lack of achievement of the much needed air domination by the Luftwaffe, and thus was a factor in the cancellation of Operation Sea Lion. (53).

Role of the RAF

The RAF had used its experiences of bomber and zeppelin attacks in the First World War, as part of its strategy for developing its defenses against enemy air attacks. This strategy included the ability of detecting incoming enemy aircraft well before they were in sight, and developing the required response based on this information. The ability to detect incoming enemy aircraft well before they were in sight consisted of the Chain Home radar system, with the capacity for detecting enemy aircraft at a distance of 120 kilometers. This radar system was further augmented by the Chain Home Low radar system with the ability to detect incoming enemy aircraft at a distance of 50 kilometers. The Chain Home radar systems were additionally supported by a series of observation posts. (54)

It was this combination of the radar systems and supporting systems along with interceptor fighter aircraft of Hurricanes and Spitfires that the RAF would use to defend Britain against the expected onslaught of the Luftwaffe. Claire Chennault had developed a theory on the use of interceptor pursuit fighter aircraft to ward of enemy aircraft, and the battle of Britain would test this theory. (55).

The interceptor fighter aircraft available to the RAF was the Spitfire Mark -1 and the Hawker Hurricane Mark 1. In the Battle of Britain these fighter aircraft would have to match wits with the German bomber escort fighter aircraft consisting of the Messerschmitt Bf-109s and Messerschmitt Bf-110s, before they could attempt any destruction of the German bombers. At the start of the Battle of Britain RAF Fighter Command had at its disposal 347 Hurricanes and 160 Spitfires in fighting condition, with which to take on the Luftwaffe air power of 2,550 aircraft of different capabilities, which included bombers, ground attack aircraft, fighters, and long range reconnaissance aircraft that would be used to destroy the RAF in the air and on the ground in the attempt to achieve air domination, so important to Operation Sea Lion. The fighter aircraft component available to the Luftwaffe consisted of 656 Messerschmitt Bf-109s and 200 Messerschmitt Bf-110s that vastly outnumbered the fighter aircraft available to the RAF. The Battle of Britain demonstrated the manner in which the numerically inferior RAF prevented the numerically superior Luftwaffe from achieving the air dominance required for the launch of Operation Sea Lion. (56).

The development of the Hurricane started in 1931, when the British Air Ministry finalized the specifications of the single-seat day-night fighter that it wished to become part of the RAF. The specifications were so designed as to meet the future demands required in the performance of such an aircraft, and hence surpassed the specifications of any of the then existing fighter aircraft. These specifications included enhanced maneuverability and endurance, steep climbing rate, low landing speed, and capability to carry higher fire power in terms of a minimum of four guns. (57).

The British aircraft designing and building company Hawker was already into designing a new single seat fighter aircraft. However, it found the currently available aircraft engines unsuitable for the performance demands put out by the British Air Ministry, and therefore decided to wait for the new engine being developed by Rolls Royce that promised the desired performance. (58).

The Hurricane thus entered the service of the RAF sporting the newly developed 12-cylinder Vee piston Merlin aircraft engine from Rolls Royce. The Hurricane also sported features of a maximum speed of 342 mph, a high cruising speed of 296 mph, a maximum ceiling of 36,500, an operational range of 480 miles, which could be extended to 1090 miles with assistance of external fuel tanks, and an armament of two 40mm cannon on either wing. (59).

The freshly designed Hurricane was made available for service in the RAF nearly eight months prior to the arrival of the Spitfire. In comparison to the Spitfire, when it came into service with the RAF, the Hurricane possessed wider landing gear, had the better ability to use underprepared grass and dirt airfields. Even in the armament carrying department, the Hurricane was superior, as its weapons compartment in the thick wing had greater storage space for ammunition. Re-arming and maintaining the machine guns in the Hurricane was much easier than in the Spitfire, because of the spacing present between the gins and the ammunition boxes. This allowed the ground crews to quickly re-arm the Hurricanes and send them on their next sortie. The tubular structure of the Hurricane also made it easier for field maintenance in comparison to the Spitfire. The sturdy design of the wing made it possible for 20mm cannons to be loaded on the wings, making it the only single-engine aircraft in the Second World War to have canons mounted on both its wings. (60).

In the Battle of Britain the Hurricane was given the role of stopping the German bombers, while the Spitfires dealt with the escorting fighter aircraft. This may provide an impression that the Spitfire was given the more prestigious role in the Battle for Britain. This assumption must be viewed from the perspective that there were more German bombers in the Luftwaffe attacks than the escorting fighters, and that these bombers needed to be effectively dealt with, before they could wreck havoc on the ground assets of Britain. (61).

Just as the Hurricane was the result of the British Air Ministry requirement for a superior single-seat fighter aircraft, the Spitfire was also the result of this announcement by the British Air Ministry. The Spitfire and the Hurricane were developed parallel to each other, and were the results of the British Air Ministry announcement. The Spitfire was designed by Supermarine, which was a small company attempting a tall order. So was the case with the designer of the Spitfire at Supermarine, whose earlier designer experience was limited to flying boats and sea planes. (62).

The design submitted to the British Air Ministry for approval was for its Spitfire. The design of the Spitfire showed it as a single-seat low-winged monoplane. The design of the Spitfire was built around the ageing and outdated Goshawk engine. In fact the initial design of the Spitfire submitted to the British Air Ministry left nothing much to write home about. (63).

However, during the construction of the Spitfire, changes were made to the design of the Spitfire, as its designer Mitchell was not satisfied with his initial design of the Spitfire. These changes were to bring about improvements in the Spitfire. In November 1934, while Mitchell was still refining the design of the Spitfire, Rolls Royce announced the new Merlin engine. (64).

Mitchell decided to incorporate the Merlin as the engine for the Spitfire and refine the design of the Spitfire around the Merlin engine, as it provided better scope to meet the specifications of the British Air Ministry for its new single-seat day-night fighter. Consequent to the change in the engine for the Spitfire, and the refining of the design for it around this engine, the British Air Ministry found the Spitfire more attractive, and gave the green signal for the development of a prototype. (65).

In 1936, the first flight testing of the prototype was undertaken. To a certain extent the flight test of the Spitfire prototype was considered a success, but its flight speed at 17,000 ft fell short of the desired speed of Mitchell and Supermarine. The flight speed desired was 350 mph while the prototype achieved a flight speed of only 335 mph. Evaluation of the reasons for this failure showed that the failure was due to the fixed pitch propeller used in the prototype. A change in propeller design saw the Spitfire prototype achieve a level speed of 350 mph, satisfying Supermarine and Mitchell. They put up the Spitfire prototype for approval by the British Air Ministry. (66).

Satisfied with the performance of the Spitfire prototype, the British Air Ministry placed an order for the supply of 310 Spitfires with Supermarine on June 3, 1936. The delivery schedule in the supply contract required Supermarine to supply the initial set of the Spitfires by May 1937 and the remainder by March 1939. Thus by the start of the Battle of Britain the Spitfire was well ensconced, along with the Hurricane, as the frontline interceptor fighters of the RAF, with the role of defending the British skies from any German air attacks. (67).

The outcome of the Battle of Britain ultimately boiled down to the performance of the German fighters on one side and the RAF fighters on the other side, despite the numerical advantage enjoyed by the Luftwaffe. The Spitfire was equal to the better performing Messerschmitt Bf-109 except in some ability terms. The Messerschmitt Bf-109 had a better speed at most of the altitudes, and could climb faster than the Spitfire to a altitude of 20,000 ft. These advantages of the Messerschmitt Bf-109 were compensated by the maneuverability advantage enjoyed by the Spitfire at all altitudes. On the other hand, the Hurricane was virtually outclassed in almost all the performance parameters by the Messerschmitt Bf-109, except for its better maneuverability at low altitudes. As a consequence the Spitfire was given the role of getting the better of the escorting Messerschmitt Bf-109s in the battle of Britain, while the Hurricanes were to attack the bombers and prevent them from reaching their intended targets. (68).

The Luftwaffe’s air campaign in the Battle of Britain can be broken up into many phases. The first phase was the Kanalkampf, which lasted from the tenth of July 1940 to the seventh of August, 1940. During this campaign the intended targets were British shipping, harbors, and coastal targets. These targets were well within the effective range of the Messerschmitt Bf-109s, and the numerically superior Messerschmitt Bf-109s held the Spitfires and Hurricanes at bay, allowing the German bombers strike at convoys and coastal targets. This could be considered as the darkest hour for the Spitfires and Hurricanes in the Battle of Britain, as the Messerschmitt Bf-109s controlled the required air spaces. (69).

The second phase was called Adlerangriff or Eagle Day, and extended for fifteen days in August from 8 August, 1940 to 23 August 1940. This was the phase during which the Luftwaffe attempted to gain air superiority over the RAF, buoyed by its success during the Kanalkampf phase. The domination of the RAF included destruction of the Fighter Command’s radar, operations centers, and communications, besides driving the Spitfires and Hurricanes out of the British skies. The only strategy that Fighter Command could adopt at this juncture was to play a cat and mouse game and hang on. The limited effective range deficiency of the Messerschmitt Bf-109s was to come into play in this phase of the Luftwaffe campaign. The Messerschmitt Bf-109s were not in a position to provide air cover for the full time of the bombers run. Early warnings from the radar and operations centers allowed the Fighter Command to confront the German bombers at a more opportune time to inflict as much damage as was possible on the bombers. As a result this phase of the war was a period of attrition for both, with the Luftwaffe and the RAF suffering losses. While both sides were in a position to replace lost aircraft, both sides found it difficult to find immediate replacements for the lost pilots. (70).

The third phase of the Luftwaffe air campaign in the Battle of Britain was the phase in which the Luftwaffe attempted to do the maximum damage to the airfields and ground installations of the RAF, and also key industrial production centers. The strategy behind this move on the part of the Luftwaffe was to force the RAF to present its fighters in the skies to prevent the massive bombing campaign, and thereby force a decision on the air domination issue over British skies with the RAF fighters, for they believed the numeric superiority and capabilities of the Messerschmitt Bf-109s and Messerschmitt Bf-110s would destroy the Spitfires and Hurricanes. This was a misplaced belief, for the Messerschmitt Bf-109s were not capable of long duration engagements over British skies, and had to turn back early, thus leaving the Spitfires and Hurricanes to continue taking the toll of bombers and Messerschmitt Bf-110s. The strategy in doing maximum damage to the airfields and key aircraft production facilities was to deny the operational capabilities of RAF Fighter Command, and render it as an ineffective force, thereby giving the Luftwaffe air supremacy. The continuance of this strategy and phase of the Luftwaffe air campaign in the Battle of Britain may have run a successful course, but for an accidental incident that led to less concentration on this phase of the Luftwaffe air campaign in the Battle of Britain. (71).

During the night of August 24, 1940, a dozen German bombers on a bombing raid lost their way, and mistakenly bombed the capital city of London. The British response to the targeting of civilian areas was swift. On the following night Berlin was bombed denting the pride of Reich Marshall Goering. Reich Marshall Goering had sworn that Berlin would never be bombed, while he was in command of the Luftwaffe. The reaction of Reich Marshall Goering to the bombing of Berlin was to shift of the weight of the bombing raids on the RAF airfields and aircraft production sites to the terror bombing of the cities in Britain. (72).

The final phase of the Luftwaffe air campaign this moved away from strategically important bombing raids on the ground assets of the RAF, to punitive terror bombing raids on the cities of Britain. This was to prove costly to the Luftwaffe. The lull that this bombing strategy provided the RAF, allowed RAF Fighter Command to bring back the damaged airfields and operational command structures back into operational efficiency, and replace the losses sustained by the Hurricanes and Spitfires, The Spitfires and Hurricanes were able to come at the Luftwaffe bombers with renewed vigor, causing heavy losses of aircraft to the Luftwaffe. (73).

The tide in the battle for air supremacy in the Battle of Britain was shifting from the Luftwaffe to the RAF. More and more bombers and fighters were being lost by the Luftwaffe than the losses suffered by the RAF. Through August to October 1940, the Luftwaffe lost 1,733 aircraft in comparison to the 915 fighters lost by the RAF. The Battle of Britain could not be sustained by the Luftwaffe at this rate of loss of aircraft, and the campaign by the Luftwaffe to gain air dominance over the RAF in the Battle of Britain had failed. Hitler who was hesitant to launch Operation Sea Lion without the air dominance of the Luftwaffe, at first postponed it to the spring of 1941, and a month later cancelled Operation Sea Lion (74).

Analysis of the failure of the Luftwaffe to gain air supremacy over the RAF highlights two factors. The first was the mistake in the shifting of bomber strikes on RAF Fighter Command and its ground assets, to the terror bombing campaign of the cities of Britain. This mistake of the Luftwaffe strategy prompted by the dented pride of Reich Marshall Goering, ranks among the major mistakes of the Germans in the conduct of the Second World War. Had the Luftwaffe continued the bombing raids on RAF Fighter Command and its ground assets there is every possibility that RAF Fighter Command would have found it difficult to continue holding off the Luftwaffe, giving the Luftwaffe its desired air supremacy, which would have then led to the launching of Operation Sea Lion. The shift away from the targeting of RAF Fighter Command was the sole reason that RAF Fighter Command gained time to recoup its resources and turn the tables on the Luftwaffe. The terror bombing campaign of the Luftwaffe was just the miracle that RAF Fighter Command was praying for. (75).

The second significant factor in the failure of the Luftwaffe to gain air supremacy was the excellent performance of the outnumbered British fighter aircraft consisting of Spitfires and Hurricanes. It would be difficult to pick out to the more significant fighter aircraft between the Spitfire and the Hurricane. Each was given a specific role, which was performed, evenly matching the German fighter aircraft that attempted to prevent then from performing their designated roles. Actions of the pilots and ground crew of these aircraft were also commendable, conducting operations over the four months of the duration of the Battle of Britain under trying conditions. Thus, a strategic mistake in combination with the excellent RAF fighters, pilots, and ground crew were primarily responsible for the failure of the Luftwaffe to gain the required air supremacy over the RAF, leading to the cancellation of Operation Sea Lion. (76). The RAF played a primary role in the cancellation of Operational Sea Lion, but had a number of supporting factors in this cancellation of Operation Sea Lion.

Role of the British Intelligence in the Cancellation of Operation Sea Lion

British intelligence efforts were extremely limited immediately after the loss of France, and in the early days of the German planning of Operation Sea Lion. However, intelligence reports suggested that timing of any seaborne invasion by the Germans across the English Channel would have to be well synchronized to make use of the dual factors of high tides and the cover of dawn. This reduced the window of opportunity to just one week in a month. Based on British Intelligence efforts, the Royal Navy and coastal batteries were put on high alert. (77).

The 28 divisions of the British Home Forces presented a sorry picture to act as a deterrent force to any invasion plans of the Germans across the seas. They were undermanned, ill-equipped, and lacked mobility. It therefore became imperative that there was knowledge of the selected landing areas that would be used by German invasion force. This was a difficult job, given the length of the British coast exposed to the landings from across the English Channel. Nevertheless, historically it was the south coast of England that was the traditional route for invasions, as it was the shortest route across the English Channel. British Intelligence thus expected the landings to occur along the southern coast of Britain, and the British Home Forces in the area were beefed up to strengthen their ability to deter landings along this part of the British coastline. (78).

The limited success that British Intelligence had regarding the deployment of enemy forces in the early part of the 1940s was restricted to the German naval deployments. This information received by British Intelligence however, was not very reliable and tended to be exaggerated. For example, the Royal Navy remained unaware of the torpedo damage sustained by the German battle cruisers Scharnhorst and Gneisenau, causing them to be withdrawn from active duty and sent for repairs. (79).

Most of the intelligence on the German invasion was essentially guess work. In many instances of the invasion plans, the guesswork of intelligence was wrong. However, importantly to preventing Operation Sea Lion, British Intelligence managed to come up shreds of evidence from August 1940 onwards, which was used by intelligence to decipher more correctly the German invasion plans in Operation Sea Lion. Historically, British intelligence through their tradition and experience has proved to be useful in war situations. However, in the case of the cancellation of Operation Sea Lord, the role that British Intelligence played was minimal, and hence a minor factor in the cancellation of Operation Sea Lion. (80).

It was important to know the exact date of the planned invasion Operation Sea Lion. With the passing of August of 1940, there was more expectation that the invasion could be set for any time. Desperate measures were needed for uncovering the planned date of the invasion. The British Intelligence agencies turned to every possible source, some of which were dubious, like consulting astrologers, to uncover the planned date of the German invasion. The intelligence agencies did receive information from diplomatic sources and SIS reports, but very few of these reports really had intelligence value with regard to the date of the planned German invasion. Based on a report that emanated from the British Embassy in Washington, the Combined Intelligence Community (CIC) wrongly came to the conclusion that the Operation Sea Lion had been given the go ahead signal, and the invasion was set to occur on September 22, 1940 at 1500 hrs. No such invasion date had been ever set for the invasion by the Germans. Only preparations were on for the invasion, and the date of invasion awaited the success of the Luftwaffe in achieving air supremacy over the RAF. On September 27, 1940, the CIC based on an SIS report provided an understanding that the preparations for Operation Sea Lion were complete, and that the date of invasion was yet to be fixed. The confusion in the CIC on Operation Sea Lion, and the date of its launch continued to be part of their intelligence gathering and analyzing efforts. Even when Hitler was considering the cancellation Operation Sea Lion, intelligence sources still conveyed the impression of an imminent invasion of England. (81).

Photo Reconnaissance Units (PRU) and Enigma decrypts were providing more reliable information on the Operation Sea Lion. Photographs from PRU provided the first clue in the preparation for Operation Sea Lion, when the existence of invasion craft and their marshalling were revealed. Though Enigma decrypts could not provide clues to the strategic thinking on the part of the Germans regarding Operation Sea Lion, it threw some light on the complex Operation Sea Lion plans. (82).

On September 21, 1940 an Enigma decrypt for the first time revealed the German code name Sea Lion for the invasion plans of Britain, amd also confirmed that in the mind of Hitler there was in existence the desire to invade Britain, though the date of the planned invasion remained elusive. (83).

It was again evidence provided by PRU and Enigma decrypts that were useful in realizing the diminishing threat from Operation Sea Lion. On September 20, 1940, PRU input showed that there was reduced Kriegsmarine activity in the English Channel, as five destroyers and a torpedo boat was withdrawn, and the numbers of marshaled barges were declining. Towards the end of September 1940, PRU had conclusive evidence of the reduction of barges brought together for a possible invasion. The number of barges that were early visible in the five main ports situated between Flushing and Bologne had reduced from 1004 to 691. However, intelligence analysts suggested that this may be a tactical strategy to reduce the losses of barges that were occurring because of RAF bombings on the barges at these ports. Further evidence of the diminishing threat from Operation Sea Lord came from Enigma decrypts. On October 25, 1940, a decrypted Enigma message pointed to the Luftwaffe closing down one of its administrative offices that was a liaison office with the invasion forces. On October 13^th, when Hitler postponed Operation Sea Lion to 1941 spring, the SIS did pick up the information from one of its sources, but gave it minimal importance, because it believed that the information was unreliable. (84).

From the beginning of October 1940, the pall of gloom over an impending German invasion was lifted at Intelligence Headquarters at Whitehall, even though there was no concrete evidence to suggest the same. Nevertheless there were indications that Germans were disinclined to go ahead with their invasion plans. Consequently CIC changed the status of the invasion from possibly occurring at any time, to indefinite in all its status reports. This status was further reinforced when CIC nearly threw light on Operation Sea Lion or really now the absence of Operation Sea Lion. Germany in all probability was keeping up a charade of Operation Sea Lion to confuse British Intelligence to divert British efforts, and prevent the fall in morale in Germany, should knowledge of the cancellation of Operation Sea Lion be made public. The Joint Intelligence Community however, retained its opinion that Operation Sea Lion remained a threat for as long as the Luftwaffe was numerically superior to the RAF. The failure of the Luftwaffe to gain air superiority over the RAF, the worsening weather conditions as winter approached, and the enhanced strength of the British ability to prevent an invasion were all combining in October of 1940 to make it impossible for Operation Sea Lion to succeed. (85).

The last British Intelligence alarms on Operation Sea Lion were received on October 18, 1940. However, by October 21, 1940 the Chiefs of Staff and the CIC arrived at the conclusion that danger of Operation Sea Lord had passed. On October 30, 1940 the Defense Committee and the Prime Minister believed that threat from Operation Sea Lion had become remote. (86). The British Intelligence did have their work cut out in trying to uncover the plans of Operation Sea Lion, to reliable provide intelligence for countering the threat of operation Sea Lion. Admittedly they were not always successful, but manfully strove to provide shreds of useful information for countering the threat of Operation Sea Lion. The British Intelligence may not have played a major role in the cancellation of Operation Sea Lion, but it can safely be said that British Intelligence remains a factor, though in a minor way in the cancellation of Operation Sea Lion.

The Role of the Royal Navy

The role of the Navy in the cancellation of Operation Sea Lion goes back to its traditional strength, the sea barrier that the English Channel presented, and the Battle of Norway. In any comparison between the might of Britain and Germany at the start of the Second World War, it is the Royal Navy that presented a stronger picture than the Kriegsmarine. The Royal Navy had history on its side as a naval power to be reckoned with, and at the start of the war was easily at an advantage with the Kriegsmarine in terms of the number of ships available at its disposal. The Battle of Norway was the first confrontation between the two sides apart from the phony war that took place during the First World War. (87).

The Kriegsmarine under Hitler was a far cry from the German Navies of the past. The naval policy of Hitler had led to the development of the Kriegsmarine as a modern naval force having five battle ships and an adequate complement of smaller fighting vessels, and proportional representation provided to each of the naval categories. While this was a significant advance over the type and structure of the earlier German navies, the Kriegsmarine was still a far cry from any kind of parity with the Royal Navy. (88).

It was in the Battle of Norway from May 9, 1940 onwards that the Royal Navy and the Kriegsmarine tested their strengths against each other. While both sides suffered losses, it was the Kriegsmarine that took the brunt of losing a far larger number of their ships in different categories. The losses sustained by the Kriegsmarine included eight of its modern destroyers, one heavy and one light cruiser, with another light cruiser also being possibly lost. Damage was sustained to one battle ship, one heavy cruiser and one or more light cruisers. Taking into consideration the earlier loss of a pocket battle ship and several destroyers and light cruisers, the Kriegsmarine was a highly depleted naval force after the Battle of Norway. (89).

The significance of these heavy losses would be extended to the capacity of the Kriegsmarine to provide support for any invasion of Britain, and have its impact on Operation Sea Lion. This can be seen in these words of Sir Winston Churchill, then Prime Minister of Britain “On the other hand, at the end of June 1940, a momentous date, the effective German Fleet consisted of no more than one cruiser, two light cruisers, and four destroyers. Although many of their damaged ships, like ours, could be repaired, the German Navy was no factor in the supreme issue of the invasion of Britain”. (90)

The German Navy was considered to be the weakest link among the three senior services in the eyes of strategic planning by the German High Command. Even in the Battle for Norway, the German Navy was tasked with only affecting the landings and not by any measure to test its strength against the Royal Navy. Once the landings were affected the German Navy was supposed to withdraw from the area, leaving with Luftwaffe to deal with the threat of the Royal. In what was to be a limited engagement between the German Navy and the Royal Navy, the German Navy was badly mauled heightening the fears within the German Navy and the German High Command on the whole, on the ability of the German Navy to support Operation Sea Lion without the air cover of the Luftwaffe. (91)

Even without the losses suffered by the German Navy, there is doubt expressed whether an intact German Navy could have prevented the evacuation of Dunkirk or supported an invasion of Britain across the English Channel given the strength of the Royal Navy. There is no doubt that the German losses at Norway only made the situation more comfortable for the Royal Navy (92).

Transporting the invasion forces in Operation Sea Lord, in any case would remain the responsibility of the German Navy. The unease with which the officers faced this responsibility is seen in the interviews conducted with senior German naval officers after the Second World War. The German Navy already found the task of marshalling the landing craft flotillas of the invasion fleet, the sailing out of these flotillas from the ports in the prescribed times, and taking up the required formations, within the harbor, and sailing across the English Channel in a tight formation during night time with cross currents a hard task by itself. British countermeasures would surely swing into place the moment the flotilla was sighted, and leading these counter measures would be the far-superior Royal Navy, which would be followed by the RAF. Even were the Luftwaffe to gain air supremacy over the RAF, and ensure their absence from the scene, besides attacking the Royal Navy ships, the German Navy did not believe that the Royal Navy could be prevented from breaking up the invasion fleet, and making the landing of the German Army in effective numbers difficult. (93).

In addition, in the opinion of the German Navy, the preparations for the transport flotilla had to be made on enemy territory that carried severe risks to secrecy of the build up, and possible sabotage to the transport flotilla, or the transport routes of the flotilla. Furthermore, the Royal Navy still remained practically intact, even after the Battle for Norway, unlike the condition of the German Navy. Strong opposition from the Royal Navy with all the force available at its disposal could be expected. The interdiction of the transport flotilla by the Royal Navy could be expected to begin just as soon as the flotilla moved into the English Channel. There was minimal faith reposed by the German Navy in the ability of the Luftwaffe to totally prevent the interdiction of the flotilla by the Royal Navy. Even at the height of the Luftwaffe domination of the air space during the early days of the Battle of Britain, the Luftwaffe was unable to prevent the cruisers and destroyers of the Royal Navy from presenting themselves in the western Channel ports, from where they posed a real threat to the invasion army. The German Navy did not have the ability or strength to attack the British Fleet during any requirement at the time of Operation Sea Lion. At the most they could put in place a diversion strategy to draw away some elements of the British Fleet, reducing the strength of the Royal Navy that would be available for interdicting the invasion fleet. (94).

Another factor that needed to be taken into consideration with regard to the threat of the Royal Navy to Operation Sea Lion was that even if the first wave made it through, completion of the second wave planned in Operation Sea Lion would take almost eight days to complete. This was after anticipating that the returning flotilla would escape unscathed from attacks of the Royal Navy. This long time period required for completion of the second wave would only make it easier for the Royal Navy to inflict losses on the second wave, and there was no way of estimating the losses of men and material that would be incurred by the second wave, endangering the elements of the first wave that would already be on British soil, and dependent on the second wave coming through unscathed to ensure their safety and the success of Operation Sea Lion. There was no way to ensure the elimination of the threat posed by the Royal Navy to Operation Sea Lion. This is the reason why there were sighs of relief, when news of the postponement of Operation Sea Lord was received at the German Naval Command, which became even more resonant as the news of the cancellation of Operation Sea Lion was received. (95).

Conclusion

The success of Operation Sea Lion was dependent on the Luftwaffe achieving air supremacy, and the prevention of the Royal Navy from attacking the transport flotilla of the invasion fleet. This may create an impression that by the RAF denying the Luftwaffe from gaining air supremacy in the Battle of Britain the RAF was solely responsible for the cancellation of Operation Sea Lion.

An in depth evaluation of Operation Sea Lion, and the reasons that led to its cancellation has shown that there were several other factors, some major and others minor that in combination with the RAF preventing the Luftwaffe from achieving air supremacy led to the cancellation of Operation Sea Lion.

Allowing the evacuation at Dunkirk of the defeated BEF was a mistake on the part of the Germans, as the BEF in essence made up the heart of the British Army. The return of the large number of soldiers beefed up the ability of the British army to withstand any invasion attempts. As a consequence, Operation Sea Lion required more German troops with their equipment to be a part of the invasion force that only enhanced the risks involved in transporting the invasion force across the English Channel, thus contributing to delays, and finally to the cancellation of Operation Sea Lion.

Operation Sea Lion was flawed in its planning, as the only one invasion route was a part of strategy, and the route was along the expected lines, causing the invasion force to run against the best defended coastline of southern Britain, from the perspective of all the three senior British forces. As a result, the risks involved in Operation Sea Lion were enhanced, and when air domination by the Luftwaffe was denied by the RAF, the enormity of the risks involved in the planned route of Operation Sea Lion contributed to its cancellation.

The three senior services of Germany in terms of the Army, Air force, and Navy presented a disjointed approach to Operation Sea Lion. Elements of shifting of responsibilities, and unwillingness to work with each other to understand the capabilities and limitation that each of the three services faced in the execution of their responsibilities to Operation Sea Lion are seen. Rather than attempting to work together to reduce the impact of the limitations, each of the three services preferred to adopt a go it alone approach. In addition, commitment Operation Sea Lion was lacking. This lack of cooperation and commitment for the success of Operation Sea Lion contributed to the cancellation of Operation Sea Lion.

British strategic planning had worked towards enhancing the ability to thwart enemy attacks from across the English Channel. The advantages of these efforts made it more difficult for enemy attacks, with particular emphasis on air attacks to be singularly effective. By contributing to the reduced impact of enemy air attacks, British strategic planning contributed to the success of the RAF in thwarting the air domination efforts of the Luftwaffe, and through that contributed to the cancellation of Operation Sea Lion.

The radar systems and the visual sighting systems playing the role of eyes and ears for the RAF, played a significant role in assisting the RAF prevent the Luftwaffe from achieving air dominance in the Battle of Britain. It may be safe to claim that without the assistance provided by the radar systems and the visual sighting systems, the RAF may have been hard put to prevent the Luftwaffe from achieving the objective of air dominance. The radar systems and the visual sighting systems were a major factor in the cancellation of Operation Sea Lion.

The RAF with its excellent planes, and committed pilots and ground crew were instrumental in preventing the Luftwaffe from achieving air dominance that was so important for the success of Operation Sea Lion. There is no doubt that the RAF was a major factor in the cancellation of Operation Sea Lion.

The British Intelligence played a minor role in the cancellation of Operation Sea Lion. However, by the demonstration of its strength over the German Navy in the Battle of Norway, it put the fear into the German Navy of its capacity to attack and destroy the invasion flotilla of Operation Sea Lion. It was this fear that made the German Navy show hesitancy in Operation Sea Lion, and take extra precautions, which took up precious time, and made even Hitler doubt the success possibilities of Operation Sea Lion. The German Navy believed that even should the Luftwaffe gain air superiority over the RAF, the Royal Navy remained a definite threat to the success of Operation Sea Lion, and heaved a sigh of relief when Operation Sea Lion was cancelled, demonstrating the major role played by the Royal Navy in the cancellation of Operation Sea Lion.

Based on this evaluation, it is safe to conclude that several factors contributed in major and minor ways to the cancellation of Operation Sea Lion, and that the RAF was not the sole factor that led to the cancellation of the doomed Operation Sea Lion, the German plan to invade Great Britain during the Second World War.

References

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Bingham, F. Victor. Merlin Power: The Growl Behind Air Power in World War II, Shrewsbury, England: Airlife Publishing (2003), p.111-140.

Chun, K. S., Clayton. Aerospace Power in the Twenty-First Century: A Basic Primer, Colorado: Air University Press (2001), p.79 -85.

Churchill, Winston. Their Finest Hour, New York: Houghton Mifflin Company (1949), 266-277.

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Footnotes

1. Robin Havers, The Second World War: Europe, 1939-1943, Volume 4 (Oxford: Osprey Publishing Limited, 2002), p.62.
2. Ibid., 62
3. Ibid., 62
4. Ibid., 62
5. Ibid., 62
6. Ibid., 62
7. Ibid., 62
8. Benoit Lemay, Erich Von Manstein: Hitler’s Master Strategist, (Havertown, PA: Casemate Publishers, 2010), p.170.
9. Lt. Col. Randy McCanne, Lt. Cdr. Greg, D. Olsen, Cdr. Dario, E. Teicher, Operation Sea Lion: A Joint Critical Analysis, (Ann Arbor, MI: Nimble Books, LLC, 2010) p.4.
10. Benoit Lemay, Erich Von Manstein: Hitler’s Master Strategist, (Havertown, PA: Casemate Publishers, 2010), p.170.
11. Kenneth Macksey, Invasion: The Alternate History of the German Invasion of England (London: Greenhill Books, 1980), p.15.
12. Benoit Lemay, Erich Von Manstein: Hitler’s Master Strategist, (Havertown, PA: Casemate Publishers, 2010), p.171.
13. Ibid., 171
14. Ibid., 171
15. Ibid., 171
16. Lt. Col. Randy McCanne, Lt. Cdr. Greg, D. Olsen, Cdr. Dario, E. Teicher, Operation Sea Lion: A Joint Critical Analysis, (Ann Arbor, MI: Nimble Books, LLC, 2010) p.5.
17. Ibid.,.5
18. R. J. Thierauf, Effective Business Intelligence Systems, (Westport, CT: Greenwood Publishing Group. Inc, 2008) p.206.
19. Ibid., 206
20. Leo, J. Daugherty, Pioneers of Amphibious Warfare, 1898-1945: Profiles of Fourteen American Military Strategists, (Jefferson, NC: McFarland & Company, Inc., 2009). p.318
21. John, H. Waller. The Unseen War in Europe: Espionage and Conspiracy in the Second World War, (London: I.B. Tauris & Co Ltd., 1996), p.135.
22. Ibid., 135
23. Ibid., 136
24. Winston Churchill. Their Finest Hour, (New York: Houghton Mifflin Company, 1949), 266
25. Ibid., 268.
26. Lt. Col. Randy McCanne, Lt. Cdr. Greg, D. Olsen, Cdr. Dario, E. Teicher, Operation Sea Lion: A Joint Critical Analysis, (Ann Arbor, MI: Nimble Books, LLC, 2010) p.4.
27. Ibid., 4
28. John, H. Waller. The Unseen War in Europe: Espionage and Conspiracy in the Second World War, (London: I.B. Tauris & Co Ltd., 1996), p.164.
29. Winston Churchill. Their Finest Hour, (New York: Houghton Mifflin Company, 1949), p.268.
30. Ibid., 268.
31. Ibid., 268-272
32. Ibid., 268-272
33. Ibid., 276-277
34. Ibid., 276-277
35. T. C. James & Sebastian Cox, The Battle of Britain, (London: Frank Cass Publishers, 2000), 3.
36. Ibid., 3
37. Ibid., 5-8
38. Ibid., 8-10
39. Richard, K. Hubbard, Boaters Bowditch, (Camden, ME: International Marine, 1998), p.121
40. Egbert Keiser. Hitler on the Doorstep, Operation Sea Lion: The German Plan to Invade Britain, 1940, (London: Arms and Armour, 1997), p.167
41. Ibid., 168
42. Derek K. Hitchens. Systems Engineering: A 21^st Century Systems Methodology, (Chichester, West Sussex: John Wiley & Sons, Ltd., 2007), p.231.
43. Ibid., 231-232
44. Ibid., 233.
45. Ibid., 233.
46. Clayton, K. S. Chun, Aerospace Power in the Twenty-First Century: A Basic Primer, (Colorado: Air University Press, 2001), p.79 -80.
47. Ibid., 80
48. Ibid., 80
49. Ibid., 81
50. Ibid., 81
51. Ibid., 81
52. Ibid., 81
53. Ibid’, 81
54. Ibid’, 81-82
55. Ibid’, 82
56. Ibid’, 82
57. Victor, F. Bingham, Merlin Power: The Growl Behind Air Power in World War II, (Shrewsbury, England: Airlife Publishing, 2003), p.111
58. Ibid., 112
59. Harold, A. Skaarup, Maryland, Virginia, and Washington Warbird Survivors, (Lincoln, NE: iUniverse, Inc., 2003), p.145.
60. Victor, F. Bingham, Merlin Power: The Growl Behind Air Power in World War II, (Shrewsbury, England: Airlife Publishing, 2003), p.117
61. Jerry Scutts, Hurricane in Action, (Carrolton, TX: Squadron/Signal Publications), p.15.
62. Victor, F. Bingham, Merlin Power: The Growl Behind Air Power in World War II, (Shrewsbury, England: Airlife Publishing, 2003), p.135
63. Ibid., 136
64. Ibid., 136
65. Ibid., 139
66. Ibid., 139
67. Ibid., 140
68. Clayton, K. S. Chun, Aerospace Power in the Twenty-First Century: A Basic Primer, (Colorado: Air University Press, 2001), p.82
69. Ibid., 82 -83.
70. Ibid., 83.
71. Ibid., 83.
72. E. B. Potter, Sea Power: A Naval History, (Annapolis, Maryland: The United States Naval Institute, 1981), p.249.
73. Clayton, K. S. Chun, Aerospace Power in the Twenty-First Century: A Basic Primer, (Colorado: Air University Press, 2001), p.83
74. E. B. Potter, Sea Power: A Naval History, (Annapolis, Maryland: The United States Naval Institute, 1981), p.249-250.
75. Clayton, K. S. Chun, Aerospace Power in the Twenty-First Century: A Basic Primer, (Colorado: Air University Press, 2001), p.85
76. Ibid., 85.
77. Peter Fleming, Operation Sea Lion: The Projected Invasion of England, (New York: Simon and Shuster, 1957), p.166.
78. Ibid., 166.
79. Ibid., 167
80. Ibid., 177
81. F. H. Hinsley, British Intelligence in the Second World War, (London: Her Majesty’s Stationery Office, 1979), 187-188.
82. Ibid., 188
83. Ibid., 188
84. Ibid., 189
85. Ibid., 190
86. Ibid., 190
87. Murfett Malcolm, Naval Warfare 1919-1945: An Operational History of the Volatile War at Sea, (Abingdon, Oxon: Routledge, 2009), p.66.
88. Max Werner, Battle for the World: The Strategy and Diplomacy of the Second World War, (London: Hesperides Press, 2006), p.91
89. Ibid., p.92.
90. Henrik, O. Lunde, Hitler’s Pre-emptive War: The Battle for Norway, 1940, (Drexel Hill, PA: Casemate, 2008), p.543
91. Max Werner, Battle for the World: The Strategy and Diplomacy of the Second World War, (London: Hesperides Press, 2006), p.92
92. Henrik, O. Lunde, Hitler’s Pre-emptive War: The Battle for Norway, 1940, (Drexel Hill, PA: Casemate, 2008), p.543
93. G. H. Bennett & R. Bennett, Hitler’s Admirals (Annapolis, MD: Naval Institute Press, 2004), p.81
94. Ibid., 82
95. Ibid., 82.