World War, 1939-1945 History 38 Campaigns 34 Causes 9 Aerial operations 8 Foreign relations 8 Biography 7 Campaign 7 Secret service 7 World war, 1939-1945 7 Naval operations, American 6 Diplomatic history 5 Military intelligence 5 Underground movements 5 United States 5 1918-1945 4 Australia 4 Strategy 4 World War, 1914-1918 4 Aerial operations, Australian 3 Aerial operations, British 3 Atomic bomb 3 France 3 History, Military 3 Naval operations 3 Naval operations, British 3 Normandy 3 Prisoners of war 3 Sources 3 Aerial operations, American 2