During the joint German-Soviet invasion of Poland, which started World War II in September 1939, Germany invaded the town and the "Einsatzgruppe V" entered the town to commit various crimes against the populace. Under German occupation the town was annexed directly to Nazi Germany and was renamed "Plöhnen". The Germans established and operated a court prison in the town. In 1940, the occupiers expelled around 1,000 Poles, whose houses and workshops were then handed over to German colonists as part of the "Lebensraum" policy. In September 1940, Jews from the town and the surrounding areas were imprisoned in a ghetto. Soon a typhus epidemic broke out. A hospital, a bathhouse for the sick, a pharmacy, and a folk kitchen were organized in the ghetto. In total, 12,000 Jews were prisoners of the ghetto and from October 1942, they were sent to the Auschwitz extermination camp. In 1943 in Berlin, the Germans sentenced six members of the local Polish resistance movement, some to death. On January 16–18, 1945, shortly before retreating, the German police carried out a massacre of 78 Poles in the town.