World War, 1939-1945 Campaigns 87 History 86 Aerial operations 44 Equipment and supplies 24 Naval operations 22 Aerial operations, British 17 Naval operations, American 14 Pictorial works 12 Biography 9 Tank warfare 9 Airplanes, Military 8 Economic aspects 8 World war, 1939-1945 8 Armed Forces 7 Fighter planes 7 Secret service 7 Battles 6 Juvenile literature 5 Personal narratives, American 5 Regimental histories 5 Tanks (Military science) 5 Underground movements 5 Warships 5 Aerial operations, American 4 Causes 4 History, Military 4 Naval operations, German 4 Personal narratives 4 Submarine 4