The 6th Prussian Cavalry Division had also been ordered to the front. After passing through the line of artillery and deploying as well as the limited space permitted, it found itself face to face with fresh and completely formed troops. Marshal Bazaine had taken the precaution of substituting for the routed bodies of the IInd Corps the Guard Grenadier Division, which he had at last prevailed on himself to bring up from his unengaged left wing, but not without filling the vacancy by a Division of the IIIrd Corps. Thus the Prussian cavalry was received with such an overwhelming musketry and artillery fire that it halted, and deliberately retired, its retreat being covered by two squadrons of Uhlans, which time after time showed a front against the enemy. The cavalry had not actually engaged, but its advance had gained time and opportunity for the artillery to move further forward in one line from the spur of the wood to Flavigny.
It was now two o'clock. So far General von Alvensleben had deceived the enemy with regard to the slenderness of his force by acting incessantly on the offensive. But the battle was now at a standstill, the battalions were visibly thinned, their strength was sapped by four hours of hard fighting, and the ammunition of the infantry was almost exhausted. Not a battalion, not a battery remained in reserve behind the fighting line standing there in the fire. It was now required to conserve the success won with so much blood by acting thenceforth on the defensive.
The left wing was in especial danger, being under the fire of the powerful artillery deployed on the Roman road. Their greatly superior numbers enabled the French to extend farther and farther to the right, threatening thus completely to envelop the Prussian flank.
Marshal Canrobert, in the French centre, had discerned the right moment to press forward against Vionville with all his might. At this critical instant there was on the German side only a small detachment of the 5th Cavalry Division available to check this effort. Two brigades had necessarily been sent to strengthen the left flank, and of the 12th Brigade remaining in rear of Vionville two squadrons had been detached to the Tronville copses. The two regiments ordered to undertake the task of charging the advancing enemy--the Magdeburg Cuirassiers and the Altmark Uhlans--were consequently each but three squadrons strong, in all 800 horses.