20th century

The century from 1901 through 2000, marked by world wars, rapid technological change, decolonization, and the growth of global political and economic systems.

World War I: A global war fought from 1914 to 1918, centered in Europe and involving powers from several continents. Its devastation helped overturn empires and destabilize the postwar order.
Nuclear weapons: Weapons that release energy through nuclear fission, fusion, or both. Their destructive capacity made deterrence central to superpower strategy.
Vladimir Lenin: A Russian revolutionary who led the Bolsheviks and headed the Soviet government after 1917. His party's seizure of power founded a state that became a global ideological rival.
League of Nations: An international organization founded after World War I to prevent conflict through collective security. Its failure to stop aggression exposed weaknesses later addressed in the United Nations.
World War II: A global war fought from 1939 to 1945 between the Axis and Allied powers. Its aftermath established new superpowers and institutions for international cooperation.
United Nations: An international organization founded in 1945 to promote peace, security, and cooperation among states. It embodied efforts to manage conflict through a standing global institution.
Adolf Hitler: The dictator of Nazi Germany from 1933 to 1945 and a central instigator of World War II. His expansionism and genocidal regime drove the century's defining European catastrophe.
Holocaust: The Nazi-led genocide that murdered six million Jews and millions of other victims during World War II. It transformed debates about genocide, human rights, and the duties of states.
Russian Revolution: The upheavals of 1917 that ended imperial rule in Russia and brought the Bolsheviks to power. It created the first durable communist state and transformed global politics.
European Union: A political and economic union of European states built through treaties and shared institutions. Its development turned postwar cooperation into an unusually integrated regional system.

Linked from 2 pages