After the Bolshevik Revolution and Russian Civil War, the Soviet authorities closed down the monastery and incorporated many of the buildings into Solovki prison camp, one of the earliest forced-labor camps of the gulag during the 1920s and 1930s. "In the earliest years of the Soviet prison system, the Solovetsky Special Prison Camp (SLON) was home to a large group of . . . imprisoned writers." The camp main activity was logging, and when most of the surrounding area had been deforested, the camp was closed. Before the Second World War, a naval cadet school was opened on the island.