World War, 1939-1945 1,583 Campaigns 549 History 539 Biography 183 World war, 1939-1945 175 Aerial operations 119 World War 97 Naval operations 95 Regimental histories 71 Secret service 66 Aerial operations, British 60 Tank warfare 54 Personal narratives 52 Equipment and supplies 49 Personal narratives, British 47 Germany 46 Naval operations, American 45 History, Military 44 Personal narratives, American 43 Submarine 43 Foreign relations 41 Causes 38 Juvenile literature 37 Aerial operations, American 36 United States 36 Pictorial works 35 Great Britain 34 Military intelligence 34 World War, 1914-1918 33 Diplomatic history 32