 Complete the following phrase:  Initially commanding the 5th Mechanised Corps and the 5th Guards Tank Corps, the 6th Tank Armys first major operation was the suppression of the Korsun-Cherkassy Pocket in JanuaryFebruary 1944. It then fought in the Iassy-Kishinev Offensive during August 1944 before gaining a Guards title in September 1944. Under its new title, it was soon engaged in the 