Much has been written about D-Day, but far less is known about the planning and strategic arguments that occurred on both sides of the Atlantic, as well as those that governed German military thinking on the likelihood, and projected defence, of an Allied invasion of Festung Europa. On Churchill's initiative, planning for the re-conquest of Western Europe started as the last British soldiers returned from Dunkirk. Four years later, his vision bore fruit as the greatest amphibious landing since Xerxes crossed the Hellespont on his bridge of boats in 481 BC...