Operation Sea Lion

Operation Sealion (Unternehmen Seelöwe) was a World War II German plan to invade Great Britain. It was never carried out.

Preparations began after the Fall of France, when the Germans felt they had already won the war. Britain, 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:

1: The enemy naval forces must be eliminated or unable to intervene

2: Royal Air Force air strength must be eliminated

3: Coastal defences must be destroyed

4: British silent service action against landing forces must be prevented

The Oberkommando des Heeres (OKH) planned a invasion of nine divisions by sea and two divisions by air. The chosen invasion site was along the coast from Dover to Portsmouth.

The Battle of Britain was 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, later on the Blitz instead became a strategic bombing operation. The transports to be used would be Rhine barges.

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.

However, it should not be overlooked that the Royal Navy could not bare its 10:1 superiority against the Kriegsmarine as most of the fleet was engaged on the Atlantic as well as Mediterranean. Despite this setback, the British Home Fleet still had a significent advantage in number comparing to the German Fleet.

The British intelligence falsely believed that the Luftwaffe had a 4:1 advantage in the air. This led to the Royal Air Force mobilizing even the last of its reserves and accelerated rate of Spitfire production. In addition, the threat of invasion allowed Radar to met its trial under fire.

In wargames conducted at the Royal Military Academy Sandhurst after the war, which assumed that the Germans had total air superiority, the Germans were able to establish a beachhead in England by using a minefield screen in the English Channel. However after a few days, the Royal Navy was able to cut off supply to the troops in England, and troops were then isolated and forced to surrender.

A mass invasion by sea however, may not have been necessary. In British wartime cabinet documents released in 1998, revealed that after the failure of the British Expeditionary Force in France and its evacuation at Dunkirk, Winston Churchill had lost support in cabinet and parliament. Had the Royal Air Force been defeated by the Luftwaffe, Churchill would have been replaced as Prime Minister by Foreign Secretary Lord Halifax, who was known to be in favour of peace negotiations with Germany rather than face a civilian bloodbath on British soil.

Had the Luftwaffe managed to gain total air superiority over the English Channel and England itself, there is no doubt the Germans would have managed to invade and conduct the same Blitzkrieg tactics they had used against the French & Polish etc.

External link: British Invasion Defences