In September 1939, when Eastern Galicia , the Theological Academy was closed and its students arrested or deported. On September 15, 1941, shortly after the onset of the German invasion of the USSR, the Academy's Church of the Holy Spirit and the library were ruined by German bombings. Limited studies resumed under German occupation during the Second World War. Out of 500 students who studied at the Academy between 1941–1944, only 60 received diplomas. After the Red Army offensive recovered Lviv for the Soviets in the spring of 1945, the Theological Academy was closed, this time for decades, while many of its graduates and professors ended up in the Gulag system of prison camps. Soon afterwards at the Lviv Synod held in March 1946 under the pressure of the Soviet authorities, the Ukrainian Greek Catholic Church was forcibly "united" with the recently recreated Ukrainian Exarchate of the Russian Orthodox Church. The theological education under the UGCC, which formally "ceased to exist" in the USSR (but in reality was banned), was restricted to the underground, as well as the entire UGCC church as a whole. This period is known as the "Church of the Catacombs" in UGCC history.