Gaining resonance from 1918, pacifism joined socialist internationalism and Communists’ novel militancy. The League of Nations drew much of that sentiment, from refugees and humanitarian relief through public health and the ILO to nutritional science and development economics, claiming economic planning, scientific and technological transfer, and humanitarian cooperation for new networked expertise. Self-consciously “Europeanist” initiatives formed, including fascist ideas of a united European “great space” under Mussolini and Hitler. By 1936–1939, imperialist visions of a New Europe made population politics key to international revisionism, exchanging self-determination and minority protections for greater-national expansion and population removal. Brutally radicalized by the Nazis’ Kristallnacht (November 1938), antisemitism became a violent driver. In 1937–1941, anti-Jewish laws reversed earlier emancipation – from Poland and Romania, through Italy and Hungary, to Czecho-Slovakia, Croatia, and Vichy France. That was the ugly backcloth to Hitler’s drive for war. In September 1939, vitally enabled by Franco-British appeasement and the Nazi–Soviet Pact, Hitler invaded Poland.