World War, 1939-1945 353 History 173 Campaigns 87 Biography 41 Airplanes, Military 34 World war, 1939-1945 30 Aerial operations 29 Equipment and supplies 29 Naval operations 27 World War 22 Naval operations, American 21 Foreign relations 20 Secret service 20 Warships 19 Juvenile literature 17 Tanks (Military science) 17 Pictorial works 15 Tank warfare 15 Armed Forces 14 Germany 14 United States 13 Fighter planes 12 Military intelligence 12 Soldiers 11 Commando operations 10 Submarine 10 Aerial operations, American 9 Personal narratives, American 9 Aerial operations, British 8 Regimental histories 8