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.

The Polish Underground State [a] was a single political and military entity formed by the union of resistance organizations in occupied Poland that were loyal to the Government of the Republic of Poland in exile in London. The first elements of the Underground State were established in the final days of the German and Soviet invasion of Poland, in late September 1939. The Underground State was perceived by supporters as a legal continuation of the pre-war Republic of Poland that waged an armed struggle against the country's occupying powers: Nazi Germany and the Soviet Union. The Underground State encompassed not only military resistance, one of the largest in the world,[b] but also civilian structures, such as justice, education, culture and social services.