What was Hitler's Operation Sea Lion and why do many historians think it could have been a disaster?

Hitler (pictured c.1935) hoped to land 100,000 troops at five points on the English coast between Ramsgate, Kent, and Selsey Bill, West Sussex

Operation Sea Lion was Hitler's code name for an invasion of the United Kingdom during the Battle of Britain in the Second World War.

It was planned for September 1940, when Hitler hoped to land 100,000 troops at five points on the English coast between Ramsgate, Kent, and Selsey Bill, West Sussex. 

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 first wave of the 'exceptionally bold and daring attack' would also feature 650 tanks and 4,500 horses.

He would then deploy another 500,000 soldiers to fight inland once the Nazis had a foothold.

The Germans were confident that such an onslaught would have led to the 'rapid abandonment' of the British defences south of London.

Their first operational objective was to occupy a huge swath of south east England - from the mouth of the River Thames down to Southampton - 14 days after the invasion.

Brighton was earmarked to be the main landing area for transport ships bringing in more troops, armour and supplies during the occupation.

And just like the Allied invasion of Normandy, the Germans would have attempted to fool the British into believing the main landings were to take place elsewhere.

A diversionary attack was planned between Aberdeen and Newcastle on the North East coast. Hitler believed Operation Sea Lion would have led to a 'rapid conclusion' of the war.

But crucially the invasion was entirely dependent on the Luftwaffe gaining air superiority over the British by the middle of September. 

The RAF won the Battle of Britain between July and October 1940, scuppering Operation Sea Lion.  

Modern historians have since suggested that plans for Sea Lion were fatally flawed and would have failed spectacularly, possibly hastening the end of the war. 

The Nazis were planning to use river barges which would be towed over the Channel in tugboats, despite these being unseaworthy. 

Furthermore, the crossing would have taken hours, during which time the powerful Royal Navy could have destroyed the armada.