Prior to World War II it had a population of at least 3,200 Jews. The Germans bombarded Ustilug heavily on the morning of 22 June 1941, the day of the outbreak of war between the Soviet Union and Germany. The German Army conquered the town toward evening. The Germans established a Jewish ghetto, a "Judenrat", and a ghetto police force, and used the town′s Jews for slave labor. From time to time the Germans took groups of Jewish youth to a valley next to the Jewish cemetery and shot them. In October 1941 alone, the Germans killed 900 Jews from the town intelligentsia. The Germans transferred the remaining Jews of Ustilug to the Volodymyr-Volynskyi ghetto between September 1 and 15, 1942, and murdered them there along with the local Jews in pits prepared for the killings in the village of Piatydnie.