Polish contribution to World War II

The European theatre of World War II opened with the German invasion of Poland on Friday September 1, 1939 and the Soviet invasion of Poland on September 17, 1939. The Polish Army was defeated after more than a month of fighting. After Poland had been overrun, a government-in-exile (headquartered in Britain), armed forces, and an intelligence service were established outside of Poland. These organizations contributed to the Allied effort throughout the war. The Polish Army was recreated in the West, as well as in the East (after the German invasion of the Soviet Union).