It began with the German invasion of Poland on September 1, 1939. By the time it came to an end on V-J Day--August 14, 1945--it had involved every major power and become global in its reach. In the final accounting, it would turn out to be, in both human terms and material resources, the costliest war in history, taking the lives of forty million people. In this complete one-volume account of the war, Gilbert weaves together political, military, diplomatic,...