Rotberg was then transferred to the Red Army and fought in the Great Patriotic War. He was taken prisoner by Wehrmacht forces near the town of Porkhov in July 1941, but released in July 1942 after promising not to take up arms against the Germans.
After the Soviet Union re-occupied the Baltic states in September 1944, Rotberg was arrested by the NKVD in Tallinn. He was accused of participating in hostilities against the Red Army in 1919, of surrender to the Wehrmacht without resistance in 1941, and of living in German-occupied Estonia without taking up arms against the occupiers after his release from captivity. On 19 October 1951, he was sentenced to 25 years in prison. Rotberg died on 24 July 1953 in prison in Tayshet. He was posthumously rehabilitated on 31 October 1957.[2][3]