World War II: Soviet forces liberate the Łódź Ghetto. Of more than 200,000 inhabitants in 1940, less than 900 had survived the Nazi occupation.

The d Ghetto or Litzmannstadt Ghetto (after the Nazi German name for d) was a Nazi ghetto established by the German authorities for Polish Jews and Roma following the Invasion of Poland. It was the second-largest ghetto in all of German-occupied Europe after the Warsaw Ghetto. Situated in the city of d, and originally intended as a preliminary step upon a more extensive plan of creating the Judenfrei province of Warthegau, the ghetto was transformed into a major industrial centre, manufacturing war supplies for Nazi Germany and especially for the Wehrmacht. The number of people incarcerated in it was increased further by the Jews deported from Nazi-controlled territories.On 30 April 1940, when the gates closed on the ghetto, it housed 163,777 residents. Because of its remarkable productivity, the ghetto managed to survive until August 1944. In the first two years, it absorbed almost 20,000 Jews from liquidated ghettos in nearby Polish towns and villages, as well as 20,000 more from the rest of German-occupied Europe. After the wave of deportations to Chemno extermination camp beginning in early 1942, and in spite of a stark reversal of fortune, the Germans persisted in eradicating the ghetto: they transported the remaining population to Auschwitz and Chemno extermination camps, where most were murdered upon arrival. It was the last ghetto in occupied Poland to be liquidated. A total of 210,000 Jews passed through it; but only 877 remained hidden when the Soviets arrived. About 10,000 Jewish residents of d, who used to live there before the invasion of Poland, survived the Holocaust elsewhere.

The Workers' and Peasants' Red Army, often shortened to the Red Army, was the army and air force of the Russian Soviet Federative Socialist Republic and, after 1922, the Union of Soviet Socialist Republics. The army was established in January 1918. The Bolsheviks raised an army to oppose the military confederations (especially the various groups collectively known as the White Army) of their adversaries during the Russian Civil War. Starting in February 1946, the Red Army, along with the Soviet Navy, embodied the main component of the Soviet Armed Forces; taking the official name of "Soviet Army", until its dissolution in 1991.

The Red Army provided the largest land force in the Allied victory in the European theatre of World War II, and its invasion of Manchuria assisted the unconditional surrender of Imperial Japan. During operations on the Eastern Front, it accounted for 75–80% of casualties the Wehrmacht and Waffen-SS suffered during the war and ultimately captured the Nazi German capital, Berlin.