there, along with the 19th Volhynian Uhlan Regiment. On July 7, 1920, during the Polish–Soviet War, it was the site of a battle between a Polish unit under Wincenty Krajowski, and the Bolsheviks of Semyon Budyonny's 1st Cavalry Army. Throughout 1919–1939 Ostróg was located in close to the Polish–Soviet border, and special passes were required to enter some districts of the town. Following the 1939 Soviet invasion of Poland, Ostróg was annexed by the Soviet Union, as part of the Ukrainian Soviet Socialist Republic. An unknown number of the town's residents were forcibly sent to Siberia. The Nazi German occupation of southern Soviet Union resulted in the establishment of the Reichskommissariat Ukraine (RKU), with headquarters in Rivne. In the autumn of 1941 several large-scale mass murders took place in Volhynia-Poldolia. On 1 September 1941 2,500 Jews were shot in Ostróg. Six weeks later the ghetto was disbanded and another 3,000 people were killed. During the first six months of the German-Soviet war 300,000 Jews were killed in the territory of the Ukrainian Soviet Socialist Republic. In total 1,430,000 Ukrainian Jews were murdered in the Holocaust. In 2022, an informal sister city arrangement was established with Beaufort, South Carolina in the United States in which the residents of Beaufort raised funds to support Ostroh during the Russian invasion of Ukraine. Landmarks include Ostroh Castle on the Red Hill, with the church of the Epiphany (built in the fifteenth century) and several towers (Tatar Gate Tower and Roun "New" Tower). To the north-west from the castle stand two sixteenth-century towers. The suburb of Mezhirichi contains the Abbey of the Trinity, with a fifteenth-century cathedral and other ancient buildings. See also Ostrogski family Ivan Fyodorov (printer) Ostroh Castle Ostroh Academy National University Ostroh Academy Uherský Ostroh References External links Cities in Rivne Oblast Ostrozhsky Uyezd Wołyń Voivodeship (1921–1939) Shtetls Cities of regional significance in Ukraine Volhynian Voivodeship (1569–1795) Jewish communities destroyed in the Holocaust