1935 By the end of 1934, Stalin had eliminated all likely potential opposition to his leadership and was the unchallenged leader of both party and state. Nevertheless, he proceeded to purge the party rank and file and to terrorize the entire country with widespread arrests and executions. During the ensuing Great Terror, which included the notorious show trials of Stalin's former Bolshevik opponents in 1936-1938 and reached its peak in 1937 and 1938, millions of innocent Soviet citizens were sent off to labor camps or killed in prison. (Britannica)