Composed of convicts--soldiers who conducted "unauthorized retreats," former Soviet POWs deemed untrustworthy, and Gulag prisoners--the Red Army's penal units received the most difficult, dangerous assignments, such as breaking through the enemy's defenses. So punishing was life in these units that officers in regular formations threatened to send recalcitrant troops to penal battalions. Alexander Pyl'cyn led his penal unit through the Soviets' massive offensive in the summer of 1944, the Vistula-Oder operation into eastern Germany, and the bitter assault on Berlin in 1945. He survived the war, but 80 percent of his men did not.