Operation Sealion (Unternehmen ("Undertaking") Seelöwe in German) was a World War II German plan to invade the United Kingdom. It was never carried out.
Plan
Preparations began after the Fall of France, when the Germans felt they had already won the war in the west. The UK, however, refused to start peace talks, so more direct measures of reducing British resistance were thought of.
Grossadmiral Erich Raeder of the Kriegsmarine was responsible for the creation of numerous studies on the plausibility of a German naval assault across the English Channel. The earliest of these studies, made around November 1939, outlined the following conditions that must be met beforehand:
- The enemy naval forces must be eliminated or unable to intervene
- Royal Air Force air strength must be eliminated
- Coastal defences must be destroyed
- British silent service action against landing forces must be prevented ( Royal Navy submarines )
The Oberkommando des Heeres (OKH) planned an invasion of nine divisions by sea and two divisions by air. The chosen invasion site was along the coast from Dover to Portsmouth. The operation was postponed on September 17th, 1940, and eventually became shelved indefinitely. Adolf Hitler was still confident the UK would surrender after Russia was defeated with the launch of Operation Barbarossa in 1941. The UK would then have been isolated in Europe with no allies. The entry of the United States into the war, however, and the reversal at Moscow, meant that the window of opportunity Sealion had in succeeding was diminishing. The failure to resolve the situation in the west would fulfil O.K.H.'s earlier warning of the dangers of a "two-front war".
The Battle of Britain was part of Operation Eagle (Unternehmen Adler in German) originally intended to allow the Luftwaffe to achieve air superiority over the Royal Air Force and allow the invasion fleet to cross the English Channel. However, the change in emphasis of the bombing from RAF bases to London (the Blitz) turned it into a strategic bombing operation.
The transports to be used would be Rhine barges as the Germans had almost no specialised landing craft. This would limit the amount of artillery and tanks that could be transported.
Most current military analysts do not believe that Operation Sealion would have succeeded if undertaken. The main difficulty was the lack of German naval assets in comparison to those of the Royal Navy. In addition, the losses in men and material suffered by the German airborne troops over the Low Countries in May during the Battle of the Netherlands, could not be replaced in time for the planned operation.
The Royal Navy could not bring the whole of its tenfold superiority against the Kriegsmarine to bear. Most of the fleet was engaged on the Atlantic as well as Mediterranean. The British Home Fleet did still have a significant advantage in numbers.
British intelligence falsely believed that the Luftwaffe had a 4:1 advantage in the air. This led to the Royal Air Force mobilizing the last of its reserves and accelerating the rate of Spitfire production. In addition, the threat of invasion allowed radar to meet its trial under fire.
Test of the plan
In wargames conducted at the Royal Military Academy Sandhurst in 1974, which assumed the Luftwaffe has 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 assualt. 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 British 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 where they cut off supplies to German troops in England and prevented further reinforcement. Isolated and facing regular troops with armour and artillery the invasion force was forced to surrender.
A mass invasion by sea however, may not have been necessary. In British wartime cabinet documents released in 1998, it was revealed that after the failure of the British Expeditionary Force in France and its evacuation at Dunkirk, Winston Churchill had lost support in the cabinet and in Parliament. Had the Royal Air Force been defeated by the Luftwaffe, Churchill may have been replaced as Prime Minister by Foreign Secretary Lord Halifax, who was believed to be in favour of peace negotiations with Germany rather than face a civilian bloodbath on British soil.
See also
External links and references
