regaining its independence. After the war, Bydgoszcz was assigned to the recreated Polish state by the 1919 Versailles Treaty. Now officially Bydgoszcz again, the city belonged to the Poznań Voivodeship. The local populace was required to acquire Polish citizenship or leave the country. This led to a drastic decline in ethnically German residents, whose number within the town decreased to 11,016 in 1926. A Nazi German youth organization was subsequently founded, which distributed Nazi propaganda books from Germany among the German minority. In 1938, the city was made part of the Polish Greater Pomerania. World War II During the invasion of Poland, at the beginning of World War II, on September 1, 1939, Germany carried out air raids on the city. The Polish 15th Infantry Division, which was stationed in Bydgoszcz, fought off German attacks on September 2, but on September 3 was forced to retreat. During the withdrawal of Poles, as part of the diversion planned by Germany, local Germans opened fire on Polish soldiers and civilians. Polish soldiers and civilians were forced into a defensive battle in which several hundred people were killed on both sides. The event, referred to as the Bloody Sunday by the propaganda of Nazi Germany, which exaggerated the number of victims to 5,000 "defenceless" Germans, was used as an excuse to carry out dozens of mass executions of Polish residents in the Old Town Market Square and in the Valley of Death. Only on September 3–10, 1939, the Germans executed 192 Poles in the city. On September 5, while the Wehrmacht entered the city, German-Polish skirmishes still took place in the Szwederowo district, and the German occupation of the city began. The German Einsatzgruppe IV, Einsatzkommando 16 and SS-Totenkopf-Standarte "Brandenburg" entered the city to commit atrocities against the Polish population, and afterwards some of its members co-formed the local German police. Many of the murders were carried out as part of the Intelligenzaktion, aimed at exterminating the Polish elites and preventing the establishment of a Polish resistance movement, which emerged regardless. On September 24, the local German Kreisleiter called local Polish city officials to a supposed formal meeting in the city hall, from where they were taken to a nearby forest and exterminated. The Kreisleiter also ordered the execution of their family members to "avoid creating martyrs". By decision from September 5, 1939, one of the first three German special courts in occupied