 On 21 August 1937, district commander Komandarm 2nd rank Ivan Dubovoy was arrested during the Great Purge.In October 1939, when the Odessa Military District was created, the Crimean ASSR and Dnipropetrovsk Oblast transferred to the new district, and the district boundaries changed to include only Voroshilovgrad, Poltava, Stalino (formerly Donetsk), Sumy, Kharkov, and Chernigov Oblasts.That year, the district began rearming and reorganizing its units, but the process was not fully completed when Operation Barbarossa, the German invasion of the Soviet Union in World War II, began on 22 June 1941.