May 1940 was a month like no other. The superior German war machine blazed into France, as the Maginot Line, supposedly "as firmly fixed in place as the Pyramids," crumbled in days. With the fall of Holland and Belgium, the imminent fall of Paris, the British Army stranded at Dunkirk, and Neville Chamberlain’s government in political freefall, Winston Churchill became prime minister on this historical nadir of May 10, 1941. Britain, diplomatically isolated, was suddenly the only nation with the courage and the resolve to defy Hitler. Against this vast historical canvas, Michael Korda relates what happened and why.