On June 22, 1941, Romania joined Operation Barbarossa on the side of the Axis, in order to reclaim the lost territories of Bessarabia and Northern Bukovina, which had been annexed by the Soviet Union in June 1940. At the beginning of July 1941, Mociulschi participated in Operation München, engaging Red Army forces in Northern Bukovina, in the Cernăuți area. During World War II Mociulschi fought on the Eastern Front against the Soviet Union and was promoted to brigadier general in 1942 and to major general in 1944.