After the outbreak of World War II, the persecution of indigenous Poles, including Kashubians, intensified, and the patients of the local psychiatric hospital were murdered in Piaśnica, however, the Polish resistance movement remained present in the district. Lauenburg was also the location of the Nazi concentration camp Lauenburg, a subcamp of Stutthof. The city was occupied without resistance by the Soviet Red Army on 10 March 1945. Most of the Old Town burned in the subsequent Soviet rampage, although the Gothic Church of St. James and the Teutonic castle survived. During this time about 600 people committed suicide.