World War II

What happened

Nazi Germany invaded Poland in 1939, initiating global conflict. Japan expanded across Asia; Italy joined the Axis. Early German victories swept through Europe; the Holocaust systematized genocide across occupied lands. The tide turned with Germany's failure in Russia (1941-1943), Japan's Pacific defeats (1942-1945), and Allied landings in Normandy (1944). Germany surrendered in May 1945; Japan in August after atomic bombings and Soviet entry. Approximately 70 million died across six continents—soldiers, civilians, Holocaust victims, colonized populations facing famine. Two-thirds of the dead were non-European.

Why it mattered

World War II ended European colonialism's moral authority, created nuclear weapons and MAD doctrine, and divided the world into Soviet and American spheres. The UN, Universal Declaration of Human Rights, and the Nuremberg Trials emerged as attempts to prevent such future catastrophes. The Holocaust became history's defining genocide. Colonial independence movements accelerated; the 'Western-led liberal order' that supposedly emerged was contested by socialist and non-aligned movements.