By the end of the Civil and Polish–Soviet Wars, Timoshenko had become the commander of the Red Army cavalry forces. Thereafter, under Stalin, he became Red Army commander in Byelorussia (1933); in Kiev (1935); in the northern Caucasus and then Kharkov (1937); and Kiev again (1938). In 1939, he was given command of the entire western border region and led the Ukrainian Front during the Soviet invasion of eastern Poland. He also became a member of the Communist Party's Central Committee. Due to being a loyal friend of Stalin, Timoshenko survived the Great Purge to become the Red Army's senior professional soldier.