On January 17, 1945, the Soviet army entered Warsaw and cleared German resistance. From the article:
"Soviets capture Warsaw - HISTORY
Soviet troops liberate the Polish capital from German occupation.
Warsaw was a battleground since the opening day of fighting in the European theater. Germany declared war by launching an air raid on September 1, 1939, and followed up with a siege that killed tens of thousands of Polish civilians and wreaked havoc on historic monuments. Deprived of electricity, water, and food, and with 25 percent of the city’s homes destroyed, Warsaw surrendered to the Germans on September 27.
The USSR had snatched a part of eastern Poland as part of the “fine print” of the Molotov-Ribbentrop Pact (also known as the Hitler-Stalin Pact) signed in August 1939, but soon after found itself at war with its “ally.” In August 1944, the Soviets began pushing the Germans west, advancing on Warsaw. The Polish Home Army, fearful that the Soviets would march on Warsaw to battle the Germans and never leave the capital, led an uprising against the German occupiers. The Polish residents hoped that if they could defeat the Germans themselves, the Allies would help install the Polish anticommunist government-in-exile after the war. Unfortunately, the Soviets, rather than aiding the Polish uprising, which they encouraged in the name of beating back their common enemy, stood idly by and watched as the Germans slaughtered the Poles and sent survivors to concentration camps. This destroyed any native Polish resistance to a pro-Soviet communist government, an essential part of Stalin’s postwar territorial designs.
After Stalin mobilized 180 divisions against the Germans in Poland and East Prussia, Gen. Georgi Zhukov’s troops crossed the Vistula north and south of the Polish capital, liberating the city from Germans—and grabbing it for the USSR. By that time, Warsaw’s prewar population of approximately 1.3 million had been reduced to a mere 153,000."