In April 1945 Churchill said to Sir Alan Brooke, Chief of the Imperial General Staff, 'There is only one thing worse than fighting with allies, and that is fighting without them!' When he became Prime Minister on 10 May 1940 Churchill was without allies. Dunkirk and the Battle of Britain saved Britain from immediate defeat, but it was evident that Britain alone could never win the war. Walter Reid, the author of several acclaimed works on 20th-century military history, brings together the result of recent research to create a powerful narrative which reveals how much time and energy Churchill devoted to fighting the war that was excluded from the official accounts: the war with his allies.