A DETAILED wartime invasion plan of Britain has been unearthed – and it reveals Dorset could have been in the firing line if Hitler's Germany had won.

The "chilling" document, compiled in the summer of 1940, contains reconnaissance photographs and maps of Studland Bay and Christchurch Bay.

The dossier is a stark reminder of how well prepared a German invading force would have been had the Luftwaffe not been rebuffed by the RAF in the Battle of Britain.

The pack is titled 'Militargeograogische Angaben uber England', which translates to 'military geographic information about England'. It was sent to German headquarters in western Europe in readiness for Operation Sea Lion – the German invasion of Britain.

Two months after the document was sent, 330,000 Allied troops were evacuated from Dunkirk.

Historians say the images, likely taken from tourism postcards, were distributed to give German troops the best idea of the landscape they would encounter after landing on British shores.

Other colour-coded geological maps show soil types in the land for the county so the Germans knew which Panzer tanks could be used.

Four years later, the Allies issued similar plans of the Normandy coast ahead of D-Day to prepare their men for the landings.

The German pack has been consigned for sale by a European private collector with C&T Auctions of Ashford, Kent. It is expected to fetch £350.

Matthew Tredwen, specialist at C&T Auctions, said: "This is an interesting folder of booklets and maps given details of strategic areas for the German soldiers to attack and hold during the operation against the British isles in 1940.

"The booklets cover various areas of the UK and have black and white images of strategic landmarks and the coast line.

"A lot of the images were from postcards and the British did exactly the same thing with their D-Day preparations.

"It is chilling to see just how much information the Germans had amassed about Britain, and how well prepared they would have been if the invasion had been launched."

Operation Sea Lion was Hitler's code name for an invasion of the United Kingdom during the Battle of 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."

But with air losses increasing, Hitler postponed Sea Lion indefinitely on September 17 1940 and it was never put into action.

The sale takes place today, Wednesday.