World War, 1939-1945 History 36 Campaigns 33 Aerial operations 8 Campaign 7 Causes 7 Secret service 7 World war, 1939-1945 7 Biography 5 Military intelligence 5 Underground movements 5 1918-1945 4 Foreign relations 4 Naval operations, American 4 United States 4 Aerial operations, British 3 Atomic bomb 3 Australia 3 Diplomatic history 3 France 3 History, Military 3 Naval operations 3 Normandy 3 Sources 3 Strategy 3 Aerial operations, American 2 Aerial operations, Australian 2 American 2 Cryptography 2 Germany 2