World War, 1939-1945 History 38 World War, 1914-1918 16 Campaigns 14 Equipment and supplies 14 Biography 12 Foreign relations 10 Naval operations 7 Aerial operations, American 6 Aerial operations, British 6 Causes 6 Fighter planes 6 Diplomatic history 5 Military history, Modern 5 Personal narratives, American 5 Secret service 5 Tank warfare 5 War 5 Aerial operations 4 Airplanes, Military 4 Army 4 Commando operations 4 Generals 4 Great Britain 4 Naval operations, British 4 Pictorial works 4 War and society 4 Armed Forces 3 Germany 3 History, Military 3