Peace War 31 World War, 1939-1945 29 Foreign relations 24 World War, 1914-1918 24 Religious aspects 17 International relations 16 History 15 World politics 15 Politics and government 11 Disarmament 9 Study and teaching 9 International cooperation 7 Research 7 Security, International 7 Arbitration, International 6 Diplomatic history 6 Doctrines 6 Nuclear disarmament 6 Biography 5 Catholic Church 5 Nuclear warfare 5 Reconstruction (1939-1951) 5 Societies, etc 5 Congresses 4 International organization 4 Pacifism 4 Pacifists 4 Poetry 4 Vietnamese Conflict, 1961-1975 4