During the spring of 1944 the Red Army finally began wrapping up its enormously expensive eight month campaign to evict German forces from the Ukraine. The linchpin of this effort came against Army Group South's left wing - defended by its First and Fourth Panzer Armies. On March 4th Marshal of the Soviet Union Georgy Zhukov's 1st Ukrainian Front, spearheaded by the 3rd Guards Tank Army and 4th Tank Army, attacked German Army Group South's left wing. Zhukov's men forged numerous penetrations in German defensive lines already heavily weakened following the battle for the Korsun pocket.