World War, 1939-1945 Campaigns 445 History 442 Biography 145 Aerial operations 102 Naval operations 80 Aerial operations, British 57 Secret service 56 Regimental histories 52 Tank warfare 50 Equipment and supplies 45 Personal narratives, British 45 Germany 41 Naval operations, American 41 Personal narratives, American 41 Personal narratives 40 History, Military 37 Foreign relations 34 Aerial operations, American 33 Submarine 33 World War, 1914-1918 32 Juvenile literature 30 Pictorial works 30 Causes 29 Great Britain 28 Military intelligence 28 Diplomatic history 27 Airplanes, Military 26 United States 25 World war, 1939-1945 25