World War, 1939-1945 Campaigns 33 History 27 Aerial operations 10 Equipment and supplies 5 Secret service 5 Aerial operations, British 4 Biography 4 History, Military 4 Naval operations 4 Armed Forces 3 Cryptography 3 Military intelligence 3 Personal narratives, American 3 Regimental histories 3 United States 3 Western Front 3 World War 3 World War, 1914-1918 3 Aerial operations, American 2 Causes 2 Chronology 2 Diplomatic history 2 Foreign relations 2 Germany 2 Great Britain 2 Malaya 2 Naval Operations 2 Normandy (France) 2 Ordnance and ordnance stores 2