The offensive against the Third Romanian Army began at 08:50, led by the 21st and 65th Soviet Armies and the 5th Tank Army. The first two assaults were repulsed by the Romanian defenders, and the effects of the heavy artillery bombardment had actually made it more difficult for Soviet armor to navigate through the minefields and terrain. However, the lack of heavy anti-tank artillery caused the Romanian defense to collapse; a breakthrough by the 4th Tank Corps and 3rd Guards Cavalry Corps was established by noon. Soon after, the 5th Tank Army was able to gain a breakthrough against the Second Romanian Corps, followed by the Eighth Cavalry Corps. As Soviet armor navigated through the thick fog by compass, overrunning Romanian and German artillery positions, three Romanian infantry divisions began to fall back in disarray; the Third Romanian Army had been outflanked to the West and East. After receiving the news of the Soviet attack, Sixth Army headquarters failed to order the 16th and 24th Panzer Divisions, hitherto engaged in Stalingrad, to reorient themselves to bolster the Romanian defenses; instead the task was given to the seriously understrength and poorly equipped 48th Panzer Corps.