World War, 1939-1945 68 Campaigns 29 History 15 Naval operations, American 12 Juvenile literature 5 Fighter planes 4 World war, 1939-1945 4 Aerial operations 3 Equipment and supplies 3 Life Books 3 Secret service 3 Time 3 Underground movements 3 War games 3 World War 3 World war 3 Causes 2 Germany 2 Mortars (Ordnance) 2 Pacific Area 2 Peace 2 Psychological aspects 2 Regimental histories 2 Rockets (Ordnance) 2 Tank warfare 2 Tanks (Military science) 2 United States. Army 2 Aerial 1 Aerial operations, British 1 Aerial operations, Japanese 1