© NTIPicture of Penzance from Hitler's invasion dossier, which detailed plans for Nazi invasion of Britain
The book pinpoints the English coastal towns in the path of the Nazi ground assault, which was only avoided because RAF fighter pilots managed to win air supremacy in the Battle of Britain in 1940.
It also reveals that postcards identifying unmistakable landmarks including Brighton Pier, and Lands End, were given to Nazi troops to identify their targets in preparation for their blitz of the British Isles.
The original copy of the book Militargoegraphiscke Angaben uber England Sudkuste for Operation Sealion detailed every attack point and weakness along England's south coast ahead of the Germans' assault in September 1940.
It included large color maps showing every part of the south coast, from Land's End to Foreness Point in Kent.
On Sept 17 1940, Hitler was forced to postpone Operation Sealion because of the Luftwaffe's failure to gain air supremacy over England.
The Nazi offensive never took place after the German defeat in the skies, but analysts believe the book reveals what could have happened if the outcome had been different.
The 446-page dossier, which is being sold by a German collector, is expected to fetch £500 when it is auctioned in Ludlow, Shropshire, later this month.
Richard Westwood-Brookes, from Mullocks Auctioneers, said: "The book on Operation Sealion gives a fascinating insight into what life could have been like if the Germans had invaded.
© NTIMap of the south coast from a recently-found 446-page Nazi war dossier detailing Hitler's planned Operation Sealion
"The book is a chilling reminder of what could have happened 70 years ago virtually to the day, had not 'the few' won the decisive Battle of Britain and caused the vital postponement of Hitler's plan.
"It's a book with detailed maps and mile-by-mile surveys on the south coast of England, so the Germans knew where they were going and had profiles of the entire length of English coast."
Historical records show Hitler planned to invade England through six divisions of German troops heading to Kent via Folkstone and Ramsgate.
Another unit of four Nazi divisions would invade Sussex and Hampshire through Brighton and the Isle of Wight, while a third group of three German divisions would attempt to take Dorset via Lyme Bay.
Mr Westwood-Brookes added: "There are details in this book about where the Germans thought they could land safely and where they thought they might come across difficulty - it really was the blueprint for the Nazi invasion.
"There may have been shingle beaches or quicksand at the various landing points along the coast, so it gives a great insight into where Hitler's men thought they could go.
"It's the kind of book that would have been carried by a high-ranking German brigade commander as he led his forces on the way to London."
The book also contains a folding plan showing the underlying terrain on the south coast, as well as features like railways and roads.
Terry Charman, the Imperial War Museums senior historian, said: "Had the RAF been defeated in the Battle of Britain this year would have been the 70th anniversary of the German invasion.
"This book as with a lot of other material adds to our greater understanding of Hitler's plans for Operation Sealion in September 1940, which fortunately never came about because of bravery of the RAF and Allied airmen."
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