{{operational plan | name = Operation Sea Lion | partof = Western Front of the Second World War | image = | caption = | scope = Normandy, the Belgian coast line, the English Channel and the English coast line from Kent to Dorset, Isle of Wight and parts of Devon, but principally in Sussex and Kent. | type = Amphibious Invasion | location = | coordinates = | map_type = | latitude = | longitude = | map_size = | map_caption = | map_label = | planned = September 1940 | planned_by = OKW | objective = Elimination of the English home country as a base of military operations against the German Reich | target = | date = | time = | time-begin = | time-end = | timezone = | executed_by = | outcome = Eventual cancellation and diversion of German forces for Operation Barbarossa | casualties = | fatalities = | injuries = }}

Operation Sea Lion () was Germany's plan to invade the United Kingdom during the Second World War, beginning in 1940. To have had any chance of success, however, the operation would have required air and naval supremacy over the English Channel. With the German defeat in the Battle of Britain, Sea Lion was postponed indefinitely on 17 September 1940 and never carried out.

Background

By early November 1939, Adolf Hitler had decided on forcing a decision in the West by invading Belgium, the Netherlands and France. With the prospect of the Channel ports falling under ''Kriegsmarine'' (German Navy) control and attempting to anticipate the obvious next step that might entail, Grand Admiral (''Großadmiral'') Erich Raeder (head of the ''Kriegsmarine'') instructed his operations officer, Kapitän Hans Jürgen Reinicke, to draw up a document examining "the possibility of troop landings in England should the future progress of the war make the problem arise." Reinicke spent five days on this study and set forth the following prerequisites:

Elimination or sealing off of Royal Navy forces from the landing and approach areas.

Elimination of the Royal Air Force (RAF).

Destruction of all Royal Navy units in the coastal zone.

Prevention of British submarine action against the landing fleet.

In December 1939, the German Army issued its own study paper (designated ''Nordwest'') and solicited opinions and input from both the ''Kriegsmarine'' and ''Luftwaffe'' (German Air Force). The paper outlined an assault on England's eastern coast between The Wash and the River Thames by troops crossing the North Sea from Low Country ports. ''Reichsmarschall'' Hermann Göring, head of the ''Luftwaffe'', responded with a single-page letter in which he stated: "...a combined operation having the objective of landing in England must be rejected. It could only be the final act of an already victorious war against Britain as otherwise the preconditions for success of a combined operation would not be met." The ''Kriegsmarine'' response was rather more restrained but equally focused on pointing out the many difficulties to be surmounted if invading England was to be a viable option.

On 16 July 1940, following Germany's swift and successful occupation of France and the Low Countries and growing impatient with Britain's indifference towards his recent peace overtures, Hitler issued Führer Directive No. 16, setting in motion preparations for a landing in Britain. He prefaced the order by stating: "As England, in spite of her hopeless military situation, still shows no signs of willingness to come to terms, I have decided to prepare, and if necessary to carry out, a landing operation against her. The aim of this operation is to eliminate the English Motherland as a base from which the war against Germany can be continued, and, if necessary, to occupy the country completely."

Hitler's directive set four conditions for the invasion to occur:

The RAF was to be "beaten down in its morale and in fact, that it can no longer display any appreciable aggressive force in opposition to the German crossing".

The English Channel was to be swept of British mines at the crossing points, and the Strait of Dover must be blocked at both ends by German mines.

The coastal zone between occupied France and England must be dominated by heavy artillery.

The Royal Navy must be sufficiently engaged in the North Sea and the Mediterranean so that it could not intervene in the crossing. British home squadrons must be damaged or destroyed by air and torpedo attacks.

This ultimately placed responsibility for Sea Lion's success squarely on the shoulders of Raeder and Göring, neither of whom had the slightest enthusiasm for the venture and, in fact, did little to hide their opposition to it. Nor did Directive 16 provide for a combined operational headquarters under which all three service branches (Army, Navy, Air Force) could work together under a single umbrella organisation to plan, coordinate and execute such a complex undertaking (similar to the Allies' creation of SHAEF for the later Normandy landings).

Upon hearing of Hitler's intentions, Italian dictator Benito Mussolini, through his Foreign Minister Count Ciano, quickly offered up to ten divisions and thirty squadrons of Italian aircraft for the proposed invasion. Hitler initially declined any such aid but eventually allowed a small contingent of Italian fighters and bombers, the Italian Air Corps (''Corpo Aereo Italiano'' or CAI), to assist in the ''Luftwaffe's'' aerial campaign over Britain in October/November 1940.

German land forces

Air power

Battle of Britain

Beginning in August 1940, the German ''Luftwaffe'' began a series of concentrated aerial attacks (designated ''Unternehmen Adlerangriff'' or Operation Eagle Attack) on targets throughout the British Isles in an attempt to destroy the RAF (Royal Air Force) and establish air superiority over Great Britain. The campaign later became known as the Battle of Britain. However, the change in emphasis of the bombing from RAF bases to bombing London turned ''Adler'' into a strategic bombing operation. The impact of the switch in strategy is disputed. Some argue that the change in strategy lost the Luftwaffe the opportunity of winning the air battle, or air superiority. Others argue the Luftwaffe achieved little in the air battle and the RAF was not on the verge of collapse, as often claimed. Another perspective has also been put forward, which suggests the Germans could not have gained air superiority before the weather window closed. Others have pointed out that it was unlikely the Luftwaffe was ever able to destroy RAF Fighter Command. If British losses became severe, the RAF could simply have withdrawn northward and regrouped. It could then deploy when, or if, the Germans launched an invasion. Some also venture to argue Sea Lion would have failed regardless because of the weaknesses of German sea power.

The view of those that believe, regardless of a potential German victory in the air battle, that ''Sea Lion'' was still not going to succeed included a number of German General Staff members. Grand Admiral Karl Dönitz believed air superiority was "not enough". Dönitz stated, "we possessed neither control of the air or the sea; nor were we in any position to gain it". Erich Raeder, commander-in-chief of the ''Kriegsmarine'' in 1940 argued:

When Franz Halder, the Chief of the Army General Staff, heard of the state of the ''Kriegsmarine'', and its plan for the invasion, he noted in his diary, on 28 July 1940; "If that [the plan] is true, all previous statements by the navy were so much rubbish and we can throw away the whole plan of invasion".

Alfred Jodl, Chief of Operations in the OKW, argued, after Raeder argued that the ''Kriegsmarine'' could not meet the operational requirements of the Army; "then a landing in England must be regarded as a sheer act of desperation".

Limitations of the Luftwaffe

The track record of the Luftwaffe against naval combat vessels up to that point in the war was less than impressive. In the Norwegian Campaign, despite eight weeks of continuous air supremacy, the Luftwaffe sank only two British warships. The German aircrews were not trained or equipped to attack fast moving naval targets, particularly agile naval destroyers or motor torpedo boats (MTBs). The Luftwaffe also lacked armour-piercing bombs or aerial torpedo capabilities that were essential to defeating larger warships. The Luftwaffe made 21 deliberate attacks on small torpedo boats during the Battle of Britain, sinking none. The British had between 700 and 800 of these vessels in service, making it a critical threat if the Luftwaffe could not deal with the force. Only nine MTBs were lost to air attack out of 115 sunk by various means throughout the Second World War. Only nine destroyers were sunk by air attack in 1940, out of a force of over 100 operating in British waters at the time. Five were sunk while evacuating Dunkirk despite large periods of German air superiority, thousands of sorties flown, and hundreds of tons of bombs dropped against them. The Luftwaffe's record against merchant shipping was also not impressive. It sank only one in every 100 British vessels passing through British waters in 1940. Moreover, most of this total was achieved using mines.

Navy

The most daunting problem for Germany in protecting an invasion fleet was the small size of its navy. The ''Kriegsmarine'', already numerically far inferior to Britain's Royal Navy, had lost a sizable portion of its large modern surface units in April 1940 during the Norwegian Campaign, either as complete losses or due to battle damage. In particular, the loss of two light cruisers and ten destroyers was crippling, as these were the very warships most suited to operating in the Channel narrows where the invasion would likely take place. Most U-boats, the most powerful arm of the , were built for use in the open ocean and simply not suitable for operations in the relatively shallow and restricted waters of the English Channel.

Although the Royal Navy could not bring to bear the whole of its naval superiority (most of the fleet was engaged in the Atlantic and Mediterranean), the British Home Fleet still had a very large advantage in numbers. It was debatable whether British ships were as vulnerable to enemy air attack as the Germans hoped. During the Dunkirk evacuation few warships were actually sunk, despite being stationary targets. The overall disparity between the opposing naval forces made the amphibious invasion plan risky, regardless of the outcome in the air. In addition, the ''Kriegsmarine'' had allocated its few remaining larger and modern ships to diversionary operations in the North Sea.

The French fleet, one of the most powerful and modern in the world, might have tipped the balance against Britain. However, the preemptive destruction of the French fleet by the British by an attack on Mers-el-Kébir and the scuttling of the French fleet in Toulon two years later ensured that this could not happen.

Even if the Royal Navy had been neutralised, the chances of a successful amphibious invasion across the Channel were remote. The Germans had no specialised landing craft, and had to rely primarily on river barges to lift troops and supplies for the landing. This would have limited the quantity of artillery and tanks that could be transported and restricted operations to times of good weather. The barges were not designed for use in open sea and even in almost perfect conditions, they would have been slow and vulnerable to attack. There were also not enough barges to transport the first invasion wave nor the following waves with their equipment. The Germans would have needed to immediately capture a port, an unlikely circumstance considering the strength of the British coastal defences around the south-eastern harbours at that time. The British also had several contingency plans, including the use of poison gas.

Landing craft

In 1940 the German Navy was ill-prepared for mounting an amphibious assault the size of ''Operation Sea Lion''. Lacking purpose-built landing craft and both doctrinal and practical experience with amphibious warfare, the Navy was largely improvising from scratch. Some efforts had been made during the inter-war years to investigate landing military forces by sea but inadequate funding severely limited any useful progress.

The Navy had taken some small steps in remedying the landing craft situation with construction of the ''Pionierlandungsboot 39'' (Engineer Landing Boat 39), a self-propelled shallow-draft vessel which could carry 45 infantrymen, two light vehicles or 20 tons of cargo and land on an open beach, unloading via a pair of clamshell doors at the bow. But by late September 1940, only two prototypes had been delivered.

Recognising the need for an even larger craft capable of landing both tanks and infantry onto a hostile shore, the Navy began development of the 220-ton ''Marinefährprahm'' (MFP) but these too were unavailable in time for a landing on English soil in 1940, the first of them not being commissioned until April 1941.

Given barely two months to assemble a large sea-going invasion fleet, the ''Kriegsmarine'' opted to convert inland river barges into makeshift landing craft. Approximately 2,400 barges were collected from throughout Europe (860 from Germany, 1,200 from the Netherlands and Belgium and 350 from France). Of these, only about 800 were powered (some insufficiently). The rest required towing by tugs.

Barge types

Two types of inland river barges were generally available in Europe for use in ''Sea Lion'': the ''peniche'', which was 38.5 metres long and carried 360 tons of cargo, and the ''Kampine'', which was 50 metres long and carried 620 tons of cargo. Of the barges collected for the invasion, 1,336 were classified as ''peniches'' and 982 as ''Kampinen''. For simplicity’s sake, the Germans designated any barge up to the size of a standard ''peniche'' as Type A1 and anything larger as Type A2.

Type A

Converting the assembled barges into landing craft involved cutting an opening in the bow for off-loading troops and vehicles, welding longitudinal I-beams and transverse braces to the hull to improve seaworthiness, adding a wooden internal ramp and pouring a concrete floor in the hold to allow for tank transport. As modified, the Type A1 barge could accommodate three medium tanks while the Type A2 could carry four.

Type B

This barge was a Type A altered to carry and rapidly off-load the submersible tanks (''Tauchpanzers'') developed for use in ''Sea Lion''. They had the advantage of being able to unload their tanks directly into water up to in depth, several hundred yards from shore, whereas the unmodified Type A had to be firmly grounded on the beach, making it more vulnerable to enemy fire. The Type B required a longer external ramp (11 metres) with a float attached to the front of it. Once the barge anchored, the crew would extend the internally stowed ramp using block and tackle sets until it was resting on the water’s surface. As the first tank rolled forward onto the ramp, its weight would tilt the forward end of the ramp into the water and push it down onto the seabed. Once the tank rolled off, the ramp would bob back up to a horizontal position, ready for the next one to exit. The Navy High Command increased its initial order for 60 of these vessels to 70 in order to compensate for expected losses. A further 5 were ordered on 30 September as a reserve.

Type C

The Type C barge was specifically converted to carry the Panzer II amphibious tank (''Schwimmpanzer''). Because of the extra width of the floats attached to this tank, cutting a broad exit ramp into the bow of the barge was not considered advisable as it would have compromised the vessel’s seaworthiness to an unacceptable degree. Instead, a large hatch was cut into the stern, thereby allowing the tanks to drive directly into deep water before turning under their own motive power and heading towards shore. The Type C barge could accommodate up to four ''Schwimmpanzers'' in its hold. Approximately 14 of these craft were available by the end of September.

Type AS

During the planning stages of ''Sea Lion'', it was deemed desirable to provide the advanced infantry detachments (making the initial landings) with greater protection from small-arms and light artillery fire by lining the sides of a Type A barge with concrete. Wooden slides were also installed along the barge’s hull to accommodate ten assault boats (''Sturmbooten''), each capable of carrying six infantrymen and powered by a 30hp outboard motor. The extra weight of this additional armor and equipment reduced the barge’s load capacity to just 40 tons. By mid-August, 18 of these craft, designated Type AS, had been converted and another 5 were ordered on 30 September.

Type AF

The ''Luftwaffe'' had formed its own special command (''Sonderkommando'') under Major Fritz Siebel to investigate the production of landing craft for ''Sea Lion''. Major Siebel proposed giving the unpowered Type A barges their own motive power by installing a pair of 600hp surplus BMW aircraft engines on them. The Navy was highly skeptical of this venture but the Army high command enthusiastically embraced the concept and Siebel proceeded with the conversions.

The aircraft engines were mounted on a platform supported by iron scaffolding at the aft end of the vessel. Cooling water was stored in tanks mounted above-deck. As completed, the Type AF had a speed of 6 knots and a range of 60 nautical miles (unless auxiliary fuel tanks were added). Disadvantages of this set-up included an inability to back the vessel astern, limited maneuverability and the deafening noise of the engines which would have made voice commands problematic.

By 1 October, 128 Type A barges had been converted to airscrew propulsion and, by the end of the month, this figure had risen to over 200.

Performance

Overall, the converted invasion barges proved surprisingly seaworthy and did well even in 4 to 5 force winds, taking on little water and demonstrating adequate handling characteristics in the waves. During one exercise, held by General Herbert Loch’s 17th Division, only two barges suffered damage to their bow doors in 6 to 8 force winds.

The ''Kriegsmarine'' later used some of the motorized ''Sea Lion'' barges for landings on the Russian-held Baltic islands in 1941 and, though most of them were eventually returned to the inland rivers they originally plied, a reserve was kept for military transport duties and for filling out amphibious flotillas.

Panzers ashore

Providing armour support for the initial wave of assault troops was a critical concern for Sea Lion planners and much effort was devoted to finding practical ways of rapidly getting tanks onto the invasion beaches. Though the Type A barges were capable of disembarking several medium tanks onto an open beach, this could be accomplished only at low tide when the barges were firmly grounded. The time needed for assembling the external ramps also meant that both the tanks and the ramp assembly crews would be exposed to close-quarter enemy fire for a considerable period of time. A safer and faster method was needed and the Germans eventually settled on providing some tanks with floats and making others fully submersible.

Schwimmpanzer

The ''Schwimmpanzer II'' was a modified version of the Panzer II which, at 8.9 tons, was light enough to float with the attachment of long rectangular buoyancy boxes to either side of the tank's hull. The boxes were machined from aluminium stock and filled with Kapok sacks for added buoyancy. Motive power came from the tank's own tracks which were connected by rods to a propeller shaft running through each float. The ''Schwimmpanzer II'' could make 5.7 km/h in the water. An inflatable rubber hose around the turret ring created a waterproof seal between the hull and turret. The tank's 2cm gun and coaxial machinegun were kept operational and could be fired while the tank was still churning its way ashore. Because of the great width of the pontoons, ''Schwimmpanzer IIs'' were to be deployed from specially modified Type C landing barges, from which they could be launched directly into open water from a large hatch cut into the stern. The Germans converted 52 of these tanks to amphibious use prior to ''Sealion's'' cancelation.

Tauchpanzer

The ''Tauchpanzer'' or deep-wading tank (also referred to as the ''U-Panzer'' or ''Unterwasser Panzer'') was a standard Panzer III or Panzer IV medium tank with its hull made completely water-proof by sealing all sighting ports, hatches and air intakes with tape or caulk. The gap between the turret and hull was sealed with an inflatable hose while the main gun mantlet, commander’s cupola and radio operator’s machine gun were given special rubber coverings. Once the tank made it to shore, all covers and seals could be blown off via explosive cables, enabling normal combat operation.

Fresh air for both the crew and engine was drawn into the tank via an 18m long rubber hose to which a float was attached to keep one end above the water’s surface. A radio antenna was also attached to the float to provide communication between the tank crew and the transport barge. The tank’s engine was converted to be cooled with seawater and the exhaust pipes were fitted with over-pressure valves. Any water seeping into the tank’s hull could be removed via an internal bilge pump. Navigation underwater was accomplished using a directional gyro compass or by following instructions radioed from the transport barge.

Experiments conducted at the end of June and early July at Schilling, near Wilhelmshaven, showed that the submersible tanks functioned best when they were kept moving along the seabed as, if halted for any reason, they tended to sink into the sand. Obstacles such as underwater trenches or large rocks tended to stop the tanks in their tracks and it was decided for this reason that they should be landed at high tide so that any tanks so mired could be retrieved again at low tide. Submersible tanks could operate in water up to a maximum depth of .

The ''Kriegsmarine'' initially expected to use 50 specially converted motor coasters to transport the submersible tanks. But actual testing with the coaster ''Germania'' showed this to be impractical due to the ballast needed to offset the weight of the tanks and the fact that the coasters had to be grounded in order to prevent them from capsizing as the tanks were transferred by crane onto the vessel’s wooden side ramps. These difficulties led to development of the Type B barge.

By the end of August, the Germans had converted 160 Panzer IIIs, 42 Panzer IVs and 52 Panzer IIs to amphibious use. This gave them a paper strength of 254 machines, about the equivalent of an armored division. The tanks were divided into four battalions or detachments labeled ''Panzer-Abteilung'' A, B, C and D. They were to carry sufficient fuel and ammunition for a combat radius of 200km.

Specialised landing equipment

As part of a Navy competition, prototypes for a prefabricated "heavy landing bridge" or jetty (similar in function to later Allied Mulberry Harbours) were designed and built by Krupp Stahlbau and Dortmunder Union and successfully overwintered in the North Sea in 1941-42. Krupp's design won out, as it only required one day to install as opposed to twenty-eight days for the Dortmunder Union bridge. The Krupp bridge consisted of a series of 32m-long connecting platforms, each supported on the seabed by four steel columns. The platforms could be raised or lowered by heavy-duty winches in order to accommodate the tide. The German Navy initially ordered eight complete Krupp units composed of six platforms each. This was reduced to six units by the autumn of 1941, and eventually cancelled altogether when it became apparent Sea Lion would never take place.

In mid-1942, both the Krupp and Dortmunder prototypes were shipped to the Channel Islands and installed together off Alderney, where they were used for unloading materials needed to fortify the island. Referred to as the "German jetty" by local inhabitants, it remained standing for the next thirty-six years until demolition crews finally removed it in 1978-79, a testament to its durability.

The German Army developed a portable landing bridge of its own nicknamed ''Seeschlange'' (Sea Snake). This "floating roadway" was formed from a series of joined modules that could be towed into place to act as a temporary jetty. Moored ships could then unload their cargo either directly onto the roadbed or lower it down onto waiting vehicles via their heavy-duty booms. The ''Seeschlange'' was successfully tested by the Army Training Unit at Le Havre in the autumn of 1941 and later slated for use in ''Operation Herkules'', the proposed Italo-German invasion of Malta. It was easily transportable by rail.

Specialised vehicles slated for Sea Lion included the ''Landwasserschlepper'' (LWS). Under development since 1935, this amphibious tractor was originally intended for use by Army engineers to assist with river crossings. Three of them were assigned to Tank Detachment 100 as part of the invasion and it was intended to use them for pulling ashore unpowered assault barges and towing vehicles across the beaches. They would also have been used to carry supplies directly ashore during the six hours of falling tide when the barges were grounded. This involved towing a Kässbohrer amphibious trailer (capable of transporting 10-20 tons of freight) behind the LWS. The LWS was demonstrated to General Halder on 2 August 1940 by the Reinhardt Trials Staff on the island of Sylt and, though he was critical of its high silhouette on land, he recognised the overall usefulness of the design. It was proposed to build enough tractors that each invasion barge could be assigned one or two of them but the late date and difficulties in mass-producing the vehicle prevented implementation of that plan.

Broad vs. narrow front

The German Army High Command (, ''OKH'') originally planned an invasion on a vast scale, extending from Dorset to Kent. This was far in excess of what ''Kriegsmarine'' could supply, and final plans were more modest, calling for nine divisions to make an amphibious landing with around 67,000 men in the first echelon and an airborne division to support them. The chosen invasion sites ran from Rottingdean in the west to Hythe in the east.

The German Navy wanted a front as short as possible as they regarded this as more defensible. Admiral Raeder wanted a front stretching from Dover to Eastbourne, stressing that shipping between Cherbourg/Le Havre and Dorset would be exposed to attacks from the Navy based in Portsmouth and Plymouth. General Halder rejected this, saying, "From the army`s point of view I regard it as complete suicide, I might just as well put the troops that have landed straight through the sausage machine."

The battle plan called for German forces to be launched from Cherbourg to Lyme Regis, Le Havre to Ventnor and Brighton, Boulogne to Eastbourne, Calais to Folkestone, and Dunkirk and Ostend to Ramsgate. ''Fallschirmjägern'' (paratroopers) would land near Brighton and Dover. Once the coast was secured, they would push north, taking Gloucester and encircling London. There is reason to believe that the Germans would not attempt to assault the city but besiege and bombard it. German forces would secure England up to the 52nd parallel (approximately as far north as Northampton), anticipating that the rest of the United Kingdom would then surrender.

German coastal guns

With Germany's occupation of the Pas-de-Calais region in Northern France, the possibility of closing the Strait of Dover to Royal Navy warships and merchant convoys by use of land-based heavy artillery became readily apparent, both to the German High Command and to Hitler. Even the ''Kriegsmarine’s'' Naval Operations Office deemed this a plausible and desirable goal, especially given the relatively short distance, , between the French and English coasts. Orders were therefore issued to assemble and begin emplacing every Army and Navy heavy artillery piece available along the French coast, primarily at Pas-de-Calais. This work was assigned to ''Organisation Todt'' and commenced on 22 July 1940.

By early August, four traversing turrets were fully operational as were all of the Army’s railway guns. Seven of the railway guns, six 28 cm K5 guns and a single K12 gun with a range of , could only be used against land targets. The remainder, thirteen 28 cm guns and five guns, plus additional motorised batteries comprising twelve 24 cm guns and ten 21 cm guns, could be fired at shipping but were of limited effectiveness due to their slow traverse speed, long loading time and ammunition types.

Better suited for use against naval targets were the four heavy naval batteries installed by mid-September: ''Friedrich August'' with three guns; ''Prinz Heinrich'' with two 28 cm guns; ''Oldenburg'' with two 24 cm guns and, largest of all, ''Siegfried'' (later renamed ''Batterie Todt'') with a pair of guns. Fire control for these guns was provided by both spotter aircraft and by DeTeGerät radar sets installed at Blanc Nez and Cap d’Alprech. These units were capable of detecting targets out to a range of , including small British patrol craft inshore of the English coast. Two additional radar sites were added by mid-September: a DeTeGerät at Cap de la Hague and a FernDeTeGerät long-range radar at Cap d’Antifer near Le Havre.

To strengthen German control of the Channel narrows, the Army planned to quickly establish mobile artillery batteries along the English shoreline once a beachhead had been firmly established. Towards that end, 16th Army’s ''Artillerie Kommand 106'' was slated to land with the second wave to provide fire protection for the transport fleet as early as possible. This unit consisted of 24 guns and 72 guns. About one third of them were to be deployed on English soil by the end of Sea Lion’s first week.

The presence of these batteries was expected to greatly reduce the threat posed by British destroyers and smaller craft along the eastern approaches as the guns would be sited to cover the main transport routes from Dover to Calais and Hastings to Boulogne. They could not entirely protect the western approaches, but a large area of those invasion zones would still be within effective range.

The British military was well aware of the dangers posed by German artillery dominating the Dover Strait and on 4 September 1940 the Chief of Naval Staff issued a memo stating that if the Germans "...could get possession of the Dover defile and capture its gun defences from us, then, holding these points on both sides of the Straits, they would be in a position largely to deny those waters to our naval forces". Should the Dover defile be lost, he concluded, the Royal Navy could do little to interrupt the flow of German supplies and reinforcements across the Channel, at least by day, and he further warned that "...there might really be a chance that they (the Germans) might be able to bring a serious weight of attack to bear on this country". The very next day the Chiefs of Staff, after discussing the importance of the defile, decided to reinforce the Dover coast with more ground troops.

Cancellation

Both Britons and Americans believed during the summer of 1940 that a German invasion was imminent. They studied the forthcoming high tides of 5-9 August, 2-7 September, 1-6 October, and 30 October-4 November as likely dates. On 17 September 1940, however, Hitler held a meeting with ''Reichsmarschall'' Hermann Göring and Field Marshal Gerd von Rundstedt during which he became convinced the operation was not viable. Control of the skies was lacking, and coordination among three branches of the armed forces was out of the question. Later that day, Hitler ordered the postponement of the operation. He ordered the dispersal of the invasion fleet in order to avert further damage by British air and naval attacks.

The postponement coincided with rumours that there had been an attempt to land on British shores on or about 7 September, which had been repulsed with large German casualties. The story was later expanded to include false reports that the British had set the sea on fire using flaming oil. Both versions were widely reported in the American press, and in William L. Shirer's ''Berlin Diary'' but officially denied by Britain and Germany. Author James Hayward has suggested that the whispering campaign around the 'failed invasion' was a successful example of British black propaganda to bolster morale at home and in occupied Europe, and convince America that Britain was not a lost cause.

After the London Blitz, Hitler turned his attention to the Soviet Union, and lapsed, never to be resumed. However, not until 13 February 1942, after the invasion of Russia, were forces earmarked for the operation released to other duties.

Chances of success

The great majority of military historians believe Operation Sea Lion would not have succeeded. Kenneth Macksey asserts it would have only been possible if the Royal Navy had refrained from large-scale intervention and the Germans had assaulted in July 1940 (although Macksey conceded they were unprepared at that time), while others such as Peter Fleming, Derek Robinson and Stephen Bungay believe the operation would have most likely resulted in a disaster for the Germans. Len Deighton and some other writers have called the German amphibious plans a "Dunkirk in reverse".

Adolf Galland, commander of fighters at the time, claimed invasion plans were not serious and that there was a palpable sense of relief in the when it was finally called off. Field Marshal Gerd von Rundstedt also took this view and thought that Hitler never seriously intended to invade Britain and the whole thing was a bluff, to put pressure on the British Government to come to terms. In fact in November 1939 the German Naval staff produced a study (on the possibility of an invasion of Britain) and concluded that it required two preconditions, air ''and'' naval superiority, neither of which Germany ever had.

Logistics

British intelligence calculated that each German division landing on British soil would require a daily average of 300 tons of supplies. They further calculated that Folkestone, the largest harbour falling within the planned Geman landing zones, could handle 150 tons per day in the first week of the invasion (assuming all dockside equipment was successfully demolished and regular RAF bombing raids reduced capacity by 50%). Within seven days, maximum capacity was expected to rise to 600 tons per day once German shore parties made repairs to the quays and cleared the harbour of any obstacles and blockships. This meant that, at best, the nine German infantry and two airborne divisions slated for the initial landings would receive less than 20% of the 3300 tons of supplies they required each day through a port and would have to rely heavily on whatever else could be brought in directly over the beaches or air-dropped.

The capture of Dover and its harbour facilities was expected to add another 800 tons per day, raising to 40% the amount of supplies brought in through ports, but this rested on the assumption of little or no interference from the Royal Navy and RAF with the German supply convoys shuttling between the Continent and the invasion beaches.

Weather

During the period 19–26 September 1940, sea and wind conditions on and over the Channel where the invasion was set to take place were good overall and a crossing (even using converted river barges) was feasible provided the sea state remained at less than 4, which, for the most part, it did. Winds for the remainder of the month were rated as "moderate" and would not have prevented the German invasion fleet from successfully depositing the First Wave troops ashore during the ten days needed to accomplish this. Beginning the night of 27 September, strong northerly winds prevailed, making passage more hazardous, but calm conditions returned on 11–12 October and again on 16–20 October. After 20 October, light easterly winds prevailed which would have actually assisted any invasion craft travelling from the Continent towards the invasion beaches. But by the end of October, according to British Air Ministry records, very strong southwest winds (force 8) would have prohibited any non-seagoing craft from risking a Channel crossing.

German intelligence

There were a number of errors in German intelligence, not least because of the success of the double-cross system in convincing agents to defect and provide disinformation to their German superiors. Whilst some errors might not have caused problems, there were others (such as the inclusion of bridges that no longer existed or misunderstanding the usefulness of minor British roads) that would have been detrimental to German operations, and would have only added to the confusion caused by the layout of Britain's cities and the removal of road signs.

Post-war wargaming of the plan

In the wargame conducted at the Royal Military Academy Sandhurst in 1974, which assumed the had ''not'' yet won air supremacy, the Germans were able to establish a beachhead in England by using a minefield screen in the English Channel to protect the initial assault. However, the German ground forces were delayed at the "Stop Lines" (e.g. the GHQ Line), a layered series of defensive positions that had been built, each a combination of Home Guard troops and physical barriers. At the same time, the regular troops of the British Army were forming up. After only a few days, the Royal Navy was able to reach the Channel from Scapa Flow, cutting off supplies and blocking further reinforcement. Isolated and facing regular troops with armour and artillery, the invasion force was forced to surrender.

Planned occupation of Britain

Administration

According to the most detailed plans created for the planned post-invasion administration, Britain and Ireland were to be divided into six military-economic commands, with headquarters in London, Birmingham, Newcastle, Liverpool, Glasgow and Dublin. Hitler decreed that Blenheim Palace, the ancestral home of Winston Churchill, was to serve as the overall headquarters of the German occupation military government. Certain source indicates that the Germans intended to occupy Southern England only, and that draft documents existed on the regulation of the passage of British civilians back and forth between the occupied and unoccupied territories.

The OKW, RSHA and Foreign Ministry compiled lists of those they thought could be trusted to form a new government along the lines of that in occupied Norway. The list was headed by Oswald Mosley. The RSHA also felt that Harold Nicolson might prove useful in this role. OKW also expected to face armed civilian resistance.

After the war rumours also emerged about the selection of two candidates for the "viceregal" office of ''Reichskommissar für Großbritannien'' (Reichskommissar for Great Britain), which in other occupied territories (such as Norway and the Netherlands) actually entailed the granting of near-dictatorial powers to its officeholders (Josef Terboven and Arthur Seyss-Inquart, respectively). The first of these was Joachim von Ribbentrop, the German Foreign Minister and previously an ambassador to Great Britain, and the second Ernst Wilhelm Bohle, an undersecretary in the Foreign Office and the Gauleiter of the NSDAP/AO. However, no establishment by this name was ever approved by either Hitler or the Reich government during the Second World War, and was also denied by Bohle when he was interrogated by the victorious Allies (von Ribbentrop not having been questioned on the matter). After the Second Armistice at Compiègne with France, when he expected an imminent British capitulation, Hitler did however assure Bohle that he would be the next German ambassador to the Court of St. James's "if the British behave[d] sensibly".

British monarchy

A Channel 5 documentary broadcast on 16 July 2009 claimed that the Germans intended to restore Edward VIII to the throne in the event of a German occupation. Many senior Nazi officials believed the Duke of Windsor to be highly sympathetic to the Nazi government, a feeling that was reinforced by his and Wallis Simpson's 1937 visit to Germany. However, it was revealed that (despite German approaches and implications that 'some harm' might come to him otherwise) the former king had willingly allowed himself to be 'smuggled' (at personal risk) aboard a US warship to take up his new post as Governor of the Bahamas - and therefore beyond Hitler's reach. Despite rumours, the British Foreign Office later issued a statement to the effect that, "The Duke never wavered in his loyalty to Great Britain during the war".

Security

Had Operation Sea Lion succeeded, under Dr. Franz Six were to follow the invasion force to Great Britain to establish the New Order. Six's headquarters were to be in London, with regional task forces in Birmingham, Liverpool, Manchester and Edinburgh. They were provided with a list (known as The Black Book) of 2,820 people to be arrested immediately. The Einsatzgruppen were also tasked with liquidating what remained of Britain's Jewish population, which numbered over 300,000. Six had also been entrusted with the task of securing "aero-technological research result and important equipment" as well as "Germanic works of art". There is also a suggestion that he toyed with the idea of moving Nelson's Column to Berlin. 75 The RSHA planned to take over the Ministry of Information, to close the major news agencies and to take control of all of the newspapers. Anti-German newspapers were to be closed down.

It appears, based on the German police plans, that the occupation was to be only temporary, as detailed provisions for the post-occupation period are mentioned.

Deportation

According to captured German documents, the commander-in-chief of the German Army, Walther von Brauchitsch, directed that “The able-bodied male population between the ages of 17 and 45 will, unless the local situation calls for an exceptional ruling, be interned and dispatched to the Continent”. This represented about 25% of the surviving population. The UK was then to be plundered for anything of financial, military, industrial or cultural value, and the remaining population terrorised. Civilian hostages would be taken, and the death penalty immediately imposed for even the most trivial acts of resistance.

The deported male population would have most likely been used as industrial slave labour in areas of the Reich such as the factories and mines of the Ruhr and Upper Silesia. Although they may have been treated less brutally than slaves from the East (whom the Nazis regarded as sub-humans, fit only to be worked to death), working and living conditions would still have been severe.

In late February 1943 Otto Bräutigam of the Reich Ministry for the Occupied Eastern Territories claimed he had the opportunity to read a personal report by General Wagner about a discussion with Heinrich Himmler, in which Himmler had expressed the intention to kill about 80% of the populations of France and England by special forces of the SS after the German victory. In an unrelated event, Hitler had on one occasion called the English lower classes "racially inferior".

In fiction

There is a large corpus of works set in an alternate history where the German invasion of Britain is attempted or successfully carried out (see also Axis victory in World War II). These include:

Novels and short stories

*''Against the Day'', ''Through the Night'' and ''In the Morning'' by Michael Cronin

*''Collaborator'' by Murray Davies

*''SS-GB'' by Len Deighton

*''Invasion: Alternative History of the German Invasion of England, July 1940'', by Kenneth Macksey

*''Weaver: Time's Tapestry'', by Stephen Baxter

*''Peace In Our Time'' (1946 - first performance 1947) by Noël Coward

*C. S. Forester's volume of short stories ''Gold from Crete'' (1971) includes ''If Hitler had invaded England''. This follows the progress of a German invasion fleet from its embarkation in France to its destruction in the fields of Kent, and closely follows the sequence of events reported in the Sandhurst wargame three years later.

*''Resistance'' by Owen Sheers, which sets the successful invasion in 1944 after a failed invasion of Normandy rather than in 1940

*The Thursday Next novels by Jasper Fforde are set in an alternate universe in which Operation Sea Lion was successful. The German occupying force is eventually driven out, and by the time of ''The Eyre Affair'' England is a republic.

Film and television

*''Bedknobs and Broomsticks'' (1971)

*''It Happened Here'' (1966)

''An Englishman's Castle''

''When Hitler Invaded Britain'' (2004)

''Hitler's Britain'' (2002)

*Alberto Cavalcanti's 1942 film ''Went the Day Well?'' is centred on a German radar-jamming mission for ''Sea Lion'' being eventually repulsed by the efforts of the civilian population of a remote village.

*In the 1971 film ''Dad's Army'', German aircrew with photographs vital to the invasion crash land in England.

*''Jackboots on Whitehall'' (2010)

*In a 2011 episode of ''Misfits'', an alternate reality where Germany won the Second World War, depicts Britain and the gang under the rule of the Nazi occupation force.

Video and board games

*''Axis & Allies'': while playing as the Axis powers in campaign mode (which has the Axis powers winning the war), Operation Sea Lion is the mission following the failed invasion of Normandy.

*''Britain Stands Alone: Operation Sealion, 1940'', GMT Games (1994), boardgame

*''Empire Earth'': the last mission of the German campaign is to carry out Operation Sea Lion

*''Panzer General'', SSI (1994), video game; strategic simulation game: Sea Lion '40 and Sea Lion Plus (the latter with prestige points used to take over Gibraltar allowing Italian naval assistance) scenarios are available given major victories in early operations, or the Sea Lion '43 after initial delays and later major victories in North Africa or Russia.

*''Seelöwe'', Simulations Publications, Inc. (1974), boardgame: featuring July/September scenarios (army and navy plans).

*''Silent Storm''

*''Their Finest Hour: The Battle of Britain and Operation Sea Lion'', GDW (1982), boardgame: part of GDW's Europa system.

*''Turning Point: Fall of Liberty''

*''War Front: Turning Point''

''Britain Invaded!'', aka ''Operation Sealion'', Tk Computerware (1985)

See also

British anti-invasion preparations of World War II

RAF Fighter Command Order of Battle 1940

Operation Sealion Order of Battle

Operation ''Herkules'' - The planned German invasion of Malta

Operation ''Tannenbaum'' - The planned German invasion of Switzerland

Operation ''Felix'' - The planned German invasion of Gibraltar

Operation ''Grün'' - The planned German invasion of Ireland.

Alien space bats - a discussion how Operation Sea Lion relates to the plausibility of alternate histories

References

Bibliography

Burdick, Charles, Jacobsen, Hans-Adolf. (1988). ''The Halder War Diary 1939-1942''. Navatop Press, California. ISBN 1-85367-022-7

Corum, James. ''The Luftwaffe: Creating the Operational Air War, 1918-1940''. Kansas University Press. 1997. ISBN 9780700608362

ISBN 0-89141-015-5

Dönitz, Karl. ''Ten years and Twenty Days''. New York: Da Capo Press, First Edition, 1997. ISBN 0-306-80764-5.

ISBN 0-582-77294-X ISBN 0-330-24211-3

Greiner, H. 'Operation Seelowe and Intensified Air Warfare Against England up to the 30 October 1940', in Detweiler, D. ''World War II German Military Studies'', Volume 7 of 24 (New York, 1979)

ISBN 1-86105-750-4

Hooton, E.R.. Hooton, E.R. ''The Luftwaffe: A Study in Air Power, 1933-1945''. Classic Publications, London. 2010. ISBN 978-1-90653-718-0

ISBN 978-3-86755-000-0

Larew, Karl. ''The Royal Navy in the Battle of Britain''. The Historian 54:2 (1992: Winter), pp. 243–254

ISBN 0-02-578030-1 ISBN 0-679-50756-6

Raeder, Erich. ''Erich Rader, Grand Admiral'': The Personal Memoir of the Commander in Chief of the German Navy From 1935 Until His Final Break With Hitler in 1943''. New York: Da Capo Press. United States Naval Institute, 2001. ISBN 0-306-80962-1.

ISBN 0-85177-548-9

External links

British Invasion Defences

Why Sealion is not an option for Hitler to win the war (essay)

Second Why Operation Sealion Wouldn't Work (essay)

''Sealion'': an orthodox view (includes quotes from participants)

Sea Lion vs. Overlord (comparison)

Operation Sealion

Operation Sealion

Kriegsmarine nautical charts, private collection (Italy)

Category:Cancelled military operations involving Germany Category:Invasions of England Category:World War II Western European Theatre Category:German World War II special forces Category:Code names Category:Cancelled invasions Category:Cancelled military operations of World War II

ar:أسد البحر (عملية عسكرية) bg:Операция Морски лъв cs:Operace Seelöwe da:Operation Seelöwe de:Unternehmen Seelöwe es:Operación León Marino eo:Operaco Seelöwe fr:Opération Seelöwe ko:바다사자 작전 hr:Operacija Morski lav id:Operasi Singa Laut it:Operazione Leone marino he:מבצע ארי-הים lt:Jūrų liūtas (operacija) hu:Seelöwe hadművelet nl:Operatie Seelöwe ja:アシカ作戦 no:Operasjon Sjøløve pl:Operacja Lew Morski pt:Operação Leão Marinho ru:Операция «Морской лев» simple:Operation Sea Lion sk:Operácia Seelöwe sl:Operacija Morski lev sr:Операција Морски лав fi:Operaatio Seelöwe sv:Operation Seelöwe ta:சீ லயன் நடவடிக்கை tr:Denizaslanı Harekâtı uk:План «Зеельове» vi:Kế hoạch Sư tử biển zh:海獅計劃

''April Fool'' is the codename for the spy and double agent who allegedly played a key role in the downfall of the Iraqi dictator Saddam Hussein.

Overview

According to General Tommy Franks, the commander of the U.S. military in the 2003 Iraq conflict, ''April Fool'', an American officer working undercover as a diplomat, was approached by an Iraqi intelligence agent. ''April Fool'' then sold to the Iraqi false "top secret" invasion plans provided by Franks' team. This decoy deception successfully misled the Iraqi military into deploying major forces in Northern and Western Iraq in anticipation of attacks via Turkey or Jordan, which never took place. This greatly reduced the defensive capacity in the rest of Iraq and significantly facilitated the actual attacks via Kuwait and the Persian Gulf in the southeast. Inadequately defended, Baghdad fell to the U.K and U.S within a few weeks and Saddam Hussein's regime collapsed.

See also

Counter-intelligence

External links

American 'double agent' sold Baghdad false war plans, Telegraph.co.uk, August 2, 2004

Agent April Fool tricked Saddam, TimesOnline, August 1, 2004

Category:People of the Iraq War Category:Double agents Category:American spies Category:Living people Category:Article Feedback 5

ar:أبريل فوول fr:April Fool ms:April Fool (perisik)