Causes History 91 World War, 1914-1918 56 Politics and government 41 Foreign relations 32 World War, 1939-1945 27 Diplomatic history 6 Slavery 6 Colonies 5 Death 5 Mortality 5 Economic conditions 4 Commerce 3 Economic aspects 3 Peace 3 Social life and customs 3 World politics 3 Franco-Prussian War, 1870-1871 2 Industries 2 Influence 2 Intellectual life 2 International finance 2 International relations 2 Military policy 2 Pangermanism 2 Participation, French 2 Relations 2 Sectionalism (United States) 2 Territorial expansion 2 1783-1815 1