The USSR established an oppressive regime. Most of the high-ranking civil and military officials, intelligentsia and industrialists were arrested, and usually executed soon afterwards. Soviet repressions culminated on 14 June 1941 with mass deportation of around 11,000 people to Siberia, among whom more than half perished in inhumane conditions. When Operation Barbarossa (accompanied by Estonian guerrilla soldiers called "Forest Brothers") began against the Soviet Union on 22 June 1941 in the form of the "Summer War" (), around 34,000 young Estonian men were forcibly drafted into the Red Army, fewer than 30% of whom survived the war. Soviet destruction battalions initiated a scorched earth policy. Political prisoners who could not be evacuated were executed by the NKVD. Many Estonians went into the forest, starting an anti-Soviet guerrilla campaign. In July, German Wehrmacht reached south Estonia. USSR evacuated Tallinn in late August with massive losses, and capture of the Estonian islands was completed by German forces in October.