The splitting of Army Group South enabled the launching of Operation Edelweiss and Operation Fischreiher, the two main thrusts of the Army Groups. Both groups had to achieve their objectives simultaneously, instead of consecutively. The success of the initial advance was such that Hitler ordered the Fourth Panzer Army south to assist the First Panzer Army to cross the lower Don river. This assistance was not needed and Kleist later complained that Fourth Panzer Army clogged the roads and that if they had carried on toward Stalingrad, they could have taken it in July. When it turned north again two weeks later, the Soviets had gathered enough forces together at Stalingrad to check its advance.