Gilbert, Adrian. Britain Invaded: Hitler's Plans for Britain, a Documentary Reconstruction
Divergence: 1940 CE
What if: Hitler's orders delaying von Rundstedt's panzers were revoked earlier, and 150,000 British troops were captured as Dunkirk fell to the Nazis on May 29, 1940. Two months later, Operation Sealion commenced.
Summary: A Time-Life-style volume describing the fall of France and the invasion and occupation of England. But with the invasion of southern France by the US and Free British forces coupled with Soviet advances into East Prussia in 1945, capped by atomic weapons dropped on Hamburg and Nuremberg, the war still ends in an Allied victory in 1945.
Comments: Oddly, or perhaps not, the copyright page states that the title of the book is actually The Last Days of Britain: An Illustrated History. Knowledgeable alternate history readers will find the bibliography very amusing.
Published: Century 1990.