 Complete the following phrase:  The corps first existed between 1928 and 1938 in the North Caucasus as a territorial unit, and was a Cossack unit for the last two years of its existence. Reformed in June 1938, the corps fought in the Soviet invasion of Poland in September 1939 and converted into a mechanized corps in the summer of 1940. Reformed in Central Asia in January 1941, the corps served in the Anglo-Soviet invasion of Iran in August of that year, returning to Central Asia in the fall of 1941 to receive three new cavalry divisions. It remained there until September 1942, when it departed for the Stalingrad Front. During 