Nazi crimes against the Polish nation: Nazi troops massacre Polish scientists and writers in the captured Ukrainian city of Lviv.

Crimes against the Polish nation committed by Nazi Germany and Axis collaborationist forces during the invasion of Poland, along with auxiliary battalions during the subsequent occupation of Poland in World War II, included the genocide of millions of Polish people, especially the systematic extermination of Jewish Poles. These mass killings were enacted by the Nazis with further plans that were justified by their racial theories, which regarded Poles and other Slavs, and especially Jews, as racially inferior Untermenschen.

Nazi Germany, officially the German Reich and later the Greater German Reich, was the German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a totalitarian dictatorship. The Third Reich, meaning "Third Realm" or "Third Empire", referred to the Nazi claim that Nazi Germany was the successor to the earlier Holy Roman Empire (800–1806) and German Empire (1871–1918). The Third Reich, which the Nazis referred to as the Thousand-Year Reich, ended in May 1945, after 12 years, when the Allies defeated Germany and entered the capital, Berlin, ending World War II in Europe.

In July 1941, 25 Polish academics from the city of Lwów along with 25 of their family members were killed by Nazi German occupation forces. By targeting prominent citizens and intellectuals for elimination, the Nazis hoped to prevent anti-Nazi activity and to weaken the resolve of the Polish resistance movement. According to an eyewitness the executions were carried out by an Einsatzgruppe unit under the command of Karl Eberhard Schöngarth with the participation of Ukrainian translators in German uniforms.

The Ukrainian Soviet Socialist Republic, abbreviated as the Ukrainian SSR, UkrSSR, and also known as Soviet Ukraine or just Ukraine, was one of the constituent republics of the Soviet Union from 1922 until 1991. Under the Soviet one-party model, the Ukrainian SSR was governed by the Communist Party of the Soviet Union through its republican branch, the Communist Party of Ukraine.