World War, 1939-1945 1,393 History 1,283 World War, 1914-1918 810 Fiction 547 Campaigns 260 Foreign relations 227 Politics and government 219 Economic aspects 189 Biography 187 War 164 Personal narratives 118 Sources 116 Causes 111 Peace 89 Personal narratives, British 79 Diplomatic history 74 Finance 56 Underground movements 54 Vietnam War, 1961-1975 50 Literature and the war 49 Description and travel 46 History and criticism 46 Economic conditions 45 Paraguayan War, 1865-1870 44 Poetry 44 Naval operations 42 Soldiers 38 World politics 38 Jews 37 Personal narratives, American 37