War had resumed in September 1939 following a Nazi-Soviet Non-aggression pact that opened the way for a repeat partition of Poland between the two dictatorships. War ended in May 1945. By then Breslau had been besieged by the Red army for three months, before being surrendered on 6 May 1945. By that time in Breslau, along with the surrounding Silesian territories, a programme of wholesale ethnic cleansing was underway. At end of 1946 Breslau had become Wrocław and the ethnic German population had been replaced by an ethnic Polish population, many of those involved having themselves been expelled from territories in the east of Poland annexed by the Soviet Union. Helmut Kirchberg was expelled to the west, ending up in the Soviet occupation zone of what had previously been Germany. By 1946 he was working as an interpreter in the Central Administration for the Fuels industry.