1 August 1944

"The city must completely disappear from the surface of the earth and serve only as a transport station for the Wehrmacht. No stone can remain standing. Every building must be razed to its foundation."

—SS chief Heinrich Himmler, 17 October, SS officers conference

Together with earlier damage suffered in the invasion of Poland (1939)
and the Warsaw Ghetto Uprising (1943),
over 85% of Warsaw was destroyed by January 1945.

The Warsaw Uprising was a struggle by the Polish Home Army to liberate Warsaw from Nazi German occupation during World War II. The Uprising began on 1 August 1944, as part of a nationwide rebellion. It was intended to last for only a few days until the Soviet Army reached the city. The Soviet advance stopped short, however, while Polish resistance against the German forces continued for 63 days.

http://www.warsawuprising.com/