Voroshilov had been an associate of STALIN and BUDENNY during the Civil War when the three of them served in the 1st Cavalry Army. In 1934 he was appointed Commissar for Defense in charge of the mechanization of the Red Army. In this capacity he also met with the Anglo-French military mission of 1939 to discuss, inconclusively, the defense of Poland. In May 1940 as part of the re-organization of the Red Army, Voroshilov was replaced by the more able TIMOSHENKO and appointed Deputy Chairman of the Defense Committee. On 3 July 1941 in response to the German invasion, Stalin set up the State Defense Committee (GKO) composed of himself, Voroshilov, MOLOTOV, MALENKOV and BERIA. They were in charge of both the overall conduct of the war and mobilization of Russian resources. Voroshilov was given command of the armies of the Northwest Front. There he failed to check the German advance or to save Leningrad, partly because of his lack of military knowledge and partly because his troops were ill-trained and inexperienced. Because of his defeats and because he and ZHDANOV had set up a Military Soviet for the Defense of Leningrad without Stalin’s orders, Voroshilov was replaced by ZHUKOV and assigned to staff positions until the end of the war.
As a member of the State Defense Committee he played a diplomatic role. In August 1942 he served as military spokesman in talks with BROOKE and WAVELL over the possibility of an Anglo-American Air Force in Transcaucasia. In November 1943 he attended the Teheran Conference. Voroshilov signed the armistice with Hungary on behalf of the Allies and later became Head of the Soviet Control Commission of Hungary.