World War II began with the German invasion of Poland in September 1939. The secret protocols of the Molotov–Ribbentrop Pact had partitioned Lithuania and Poland into German and Soviet spheres of interest. On 19 September 1939, Vilnius was seized by the Soviet Union (which invaded Poland on 17 September). The Soviets repressed the local population and devastated city, moving assets and factories to the USSR territory, including the major Polish radio factory Elektrit, along with a part of its labor force, to Minsk in Belarus SSR. The Soviets and Lithuania concluded a mutual assistance treaty on 10 October 1939, with which the Lithuanian government accepted the presence of Soviet military bases in various parts of the country. On 28 October 1939, the Red Army withdrew from the city to its suburbs (to Naujoji Vilnia) and Vilnius was given over to Lithuania. A Lithuanian Army parade took place on 29 October 1939 through the city center. The Lithuanians immediately attempted to re-Lithuanize the city, for example by Lithuanizing Polish schools.