As Vandamme’s light cavalry deployed ahead of his corps, they observed the advance of Vincent’s hussars to their right and the Austrian Avant Garde to their left. Vandamme was confident with the knowledge that St. Sulpice’s cavalry had left the main road vearing right, connecting him to Lannes and securing his left flank. So, he resolved to push. Nearly three miles away, Lannes stood between the two roads on which his corps advanced, Demont’s division on the right near St. Sulpice and Morand to the left. Morand was already deploying, having detected the Austrian cavalry leading Ulm’s division past his left.
With decisive acts by both sides, the battle began nearly immediately. Hiller sent Vincent’s hussars in as Marulaz committed against the Austrian infantry, Pajol and St. Sulpice charged to keep the flanks of the French infantry clear. Though Pajol bested Vincent’s hussars, the other actions favored Hiller’s Austrians, but in an immediate rematch, the French doubled down, adding in the weight of Claparède’s brigade and recommitting all their cavalry. The result was decisive. Nordmann led a brave but incompetent defense against the French heavy horse as his avant garde collapsed. Hiller could be seen running towards the rear as he attempted to join the remains of Radetzky’s division, crushed by Claparède while pinned by Marulaz and flanked by Pajol. Vincent’s hussars made a death charge into Claparède victorious infantry to buy Hiller enough time to rally three battalions and attempt a rearguard.
Meanwhile two miles left of Vandamme’s victory, Morand was feeling the pressure. Hohenlohe had Lannes’s left pinned by Ulm and committed Lindenau’s grenadiers against Morand’s front. For the moment, Morand was holding, but it couldn’t last. As the defeat became total on the Austrian left, Hohenlohe felt success was in his grasp with Morand finally retreating, but just as this milestone was reached, the Austrian prince received two couriers: Lannes had deftly called for Demont to push forward through the intervening woods and Lindenau’s grenadiers were being outflanked, if he continued his pursuit of Morand, he could be taken from the rear. Worse yet, Hiller had gotten a messenger past St. Sulpice’s rampaging cuirassiers to alert his partner that all was lost on the left. Hohenlohe ordered withdrawal, and pondered if there was any way to bridge the three mile gap that spanned the distance to the refugees of Hiller’s korps.