Operation Sealion: Hitler’s Doomed Plan to Invade Britain


Great Britain’s success in holding out against Nazi Germany has become the stuff of national legend. The only country in Western Europe to successfully stand against the Nazis throughout World War Two, it was kept safe by the English Channel, thanks to which only the Channel Islands were invaded by Hitler’s troops.

But Hitler did have a plan to invade Britain, and he came close to executing it.

Reaching for Peace

Munich Conference in 1938

Munich Conference in 1938, including in front, Neville Chamberlain (far left) Hitler (center) and Mussolini (second right) Photo Credit

The attitude of Nazi Germany towards the United Kingdom was a complicated one. On the one hand, the Nazis admired the British, with their strong military tradition, their overseas empire and their northern European heritage. They saw them as kindred spirits.

On the other hand, Britain was one of the countries that had humiliated Germany in the Treaty of Versailles at the end of the First World War, and on whom Hitler intended revenge. Britain remained allied with France, one of Germany’s staunchest enemies, and had been making diplomatic maneuvers aimed at containing Germany.

Even though the British contributed troops to the failed defense of France in 1940, Hitler still hoped that Britain and Germany might make peace. Following France’s fall, he avoided preparing an invasion of Britain for a month, while he waited to see if the British would give in. But it soon became clear that they would not.

Directive No. 16

On 16th July 1940, Hitler signed Führer Directive No. 16. This gave the go-ahead for the invasion of England, a plan titled Operation Sealion. After making one last bid for peace on 19th July, he pushed ahead with the plan.

The month’s delay worked in Britain’s favor. The British had been preparing their defenses and stockpiling ammunition. On top of this, the timing would be crucial for a crossing on the English Channel. If, as the British believed, the Germans could not be ready before mid-September, then weather might hamper the invasion.

But the Germans were more ready than the British thought, and the invasion was planned for the 25th of August. Forty-one divisions would cross the Channel, along with two divisions of airborne troops. Landing along the south coast, they would encircle London, bringing the British government to its knees. It was a detailed and well-considered plan.

Preparing the Fleet

Ships in Wilhelmshaven ready for the invasion (Bundesarchiv)

Ships in Wilhelmshaven ready for the invasion. Photo Credit

As the invasion fleet was assembled, the Germans began to hit snags. Grand-Admiral Raeder pointed out that not all of the planned thirteen divisions could possibly be landed in the first wave – the boats simply didn’t exist for this, and even if they did he could not defend such a fleet against the Royal Navy. So the force was reduced to twenty-seven divisions, and the occupation of Devon dropped from the plan.

Specially modified Panzer III

Specially modified Panzer III. Photo Credit

Ingenious solutions were found to the problems of invading the British coast. Tanks were waterproofed and fitted with snorkels so that they could be dropped off in thirty feet of water and drive up onto the beaches. The French coast between Boulogne and Sangatte was filled with artillery batteries capable of firing all the way across the Channel, to give the fire support the Navy was unable to provide.

Like the Allies’ later D-Day plans, Operation Sealion was marked by daring and ingenuity.