In the northern sector of the offensive, Zhukov's 1st Belorussian Front also made rapid progress, as 9th Army was no longer able to offer coherent resistance. Its XXXVI Panzer Corps, which was positioned behind Warsaw, was pushed over the Vistula into the neighbouring Second Army sector. Warsaw was taken on 17 January, as Army Group A's headquarters issued orders for the city to be abandoned; units of the 2nd Guards and 3rd Shock Armies entering the city were profoundly affected by the devastation wrought by German forces after the Warsaw Uprising. Hitler, on the other hand, was furious at the abandonment of the 'fortress', arresting Colonel Bogislaw von Bonin, head of the Operations Branch of OKH, and sacking both the 9th Army and XXXVI Panzer Corps commanders; Generals Smilo Freiherr von Lüttwitz and Walter Fries.