The Warsaw Uprising, shortly after the war also known as the August Uprising, was a major World War II operation by the Polish underground resistance to liberate Warsaw from German occupation. It occurred in the summer of 1944, and it was led by the Polish resistance Home Army. The uprising was timed to coincide with the retreat of the German forces from Poland ahead of the Soviet advance. While approaching the eastern suburbs of the city, the Red Army halted combat operations, enabling the Germans to regroup and defeat the Polish resistance and to destroy the city in retaliation. The Uprising was fought for 63 days with little outside support. It was the single largest military effort taken by any European resistance movement during World War II.