The Fourth Army was created in August 1939 in the Belorussian Special Military District from the Bobruisk Army Group as an independent army. In September 1939, the Fourth Army took part in the Soviet invasion of Poland commanded by the future Marshal of Soviet Union V.I. Chuykov, the defender of Stalingrad. Its order of battle in that operation is listed here. Elements of the army, apparently 4th Battalion, 29th Light Tank Brigade, took part in the German–Soviet military parade in Brest-Litovsk on September 22, 1939.