Napoleon was livid at Oudinot's poor showing and demoted him to the leadership of the XII Corps. Ney, now the new army commander, was ordered to march east from Wittenberg to Baruth south of Berlin. Ney assumed command on 3 September and put his 58,000-man army in motion on the 5th. That day there was a sharp fight at Zahna in which Oudinot's corps drove Tauentzien's troops out of the town. As at Großbeeren, the III Cavalry Corps was distributed among the different units of the army. Fournier accompanied XII Corps and Lorge marched with IV Corps. The Battle of Dennewitz began at 11:00 AM on 6 September when a IV Corps infantry division, supported by Lorge and a second infantry division, attacked Tauentzien north of Dennewitz. At first the French were successful but the arrival of Bülow's corps from the west forced back Lorge and the IV Corps. The VII Corps came on the field at 1:00 PM and became involved in a see-saw combat at the village of Golsdorf on the left flank. The XII Corps belatedly arrived on the left flank starting at 3:00 PM. Just as the French began gaining ground on the left, Ney ordered the XII Corps to the right to support the badly shaken IV Corps. Though he could see it was a mistake, Oudinot obeyed the letter of his orders and marched off. Bülow, now supported by Swedish and Russian reinforcements, renewed his attack and broke through. The VII Corps might have been totally destroyed but for a "timely charge" by Defrance's cuirassiers. Even so, the battle was a disaster for the French whose flight also carried away the barely-engaged XII Corps. Ney lost 22,000 men, mostly prisoners, and 53 guns. Allied casualties at Zahna, Dennewitz, and the pursuit amounted to 10,500, almost all of them Prussian.