Lannes reached the field from the northwest, while Vandamme decended with elements of his corps from the southwest. Slowed by a tributary to the Danube River, Lannes was less advanced when Vandamme’s light cavalry reported contact with the Austrians of Hiller’s corps. Hiller’s hussar brigade under Vincent was the first element to be spotted, the 3rd Ferdinand Hussars peaked around a wooded hill and began to promptly deploy. Meanwhile, Nordman’s Avantgarde moved through a pair of small villages near the crossroads where Lannes and Vandamme intended to connect. Opposing Lannes main force, Hohenlohe split his two columns, sending his grenadier division on a central route to link up with Hiller, but swinging his infantry and cavalry under Ulm to the north, into a large area of rolling hills, and seperated from Lindenau’s grenadiers by over a mile of mostly wooded terrain.
Seeing Lannes’s closest division, under Morand, less than a mile away on a parallel route by road, Vandamme deployed his lead brigade, screening it with his light cavalry. Aiming to swing southeastward through a series of wooded hills and get behind Hiller’s advanced elements.
Lannes brought his attached cuirassier division, under St. Sulpice, and his second infantry division under Demont, crossing the tributary quickly and began immediate deployment. Spotting this from his position on the heights, Hohenlohe redirected the grenadiers northward to support Ulm, but creating a gap of just over a mile between his corps and Hiller’s.
Hiller decided to take decisive action. Seeing he was separated from Hohenlohe, with his hussars reporting Vandamme’s flanking manuever, and receiving word that Radetzky’s division was delayed due to confusion of the march order, he had to buy time. Nordman’s avantgarde anchored its grenzers in the villege against Morand’s impending attack while Vincent was ordered to take the fight to the enemy. Sweeping through the French light cavalry they swarmed into the rear of Vandamme’s lead brigade and tied up the French, buying Hiller nearly an hour. Unfortunately, it was for not. Ulm’s division was struck by Saint Sulpice before it could completely deploy and was soundly defeated, retreating backwards as Lindenau advanced to support. Demont’s division had deployed and was advancing behind the cuirassiers. Hohenlohe declared he was withdrawing. Nordman’s grenzers, supported by his uhlans, were ordered to transition to a rearguard to hold up Morand, and Radetzky’s division, finally moving, was ordered to reverse course.