World War II broke out when Germany and Russia invaded Poland on September 1, 1939. The German blitzkrieg, or lightning war, strategy was revealed: Sixty divisions of 1.5 million German soldiers invaded, with support from 2,000 tanks, 900 bombers, and 400 fighter planes. The world was shocked by the rapid progress of German forces through Poland and by the ruthlessness of the German advance; hundreds of thousands of Polish soldiers and civilians were killed or injured. Overwhelmed by the German invasion (Poland managed to mobilize around a million troops, but they had no tanks, outdated weaponry, and only a very small air force), Poland was defeated by October of 1939. Poland was partitioned between Germany and the Soviet Union.

Germany’s control of Poland allowed them to institute their program of state-sanctioned antisemitism, which banned Jews from schools, shops, and workplaces and redistributed Jewish populations from their existing housing into crowded, unsanitary ghettos. Most of these Polish Jews were then forcibly transported to concentration camps in the early 1940s (Hughs, Thomas A. & Rhoyde-Smith, John Graham. “WWII.” Britannica, 1998).