The combat of Ivrea (24 May 1800) was a French victory during Napoleon's advance into Italy early in the campaign that ended at Marengo.
The French advance guard, under General Lannes, crossed the top of the Great St. Bernard Pass on 16 May, and defeated Austrian forces at Saint Remy, Aosta and Châtillon (18 May). The French were then held up by the fort of Bard, but after the main part of Napoleon's army began to arrive Lannes was sent past Bard on mountain tracks, and continued to advance south down the Dora Bàltea valley. The next Austrian resistance came at the town of Ivrea, which was defended by a force of 3,000 cavalry and 3,000 infantry (many of whom had already been defeated once at Châtillon).
On 24 May the French attacked the town from two sides, with Lannes leading one attack and Watrin the other. The town and citadel fell after a short struggle, and the Austrians retreated south, taking up a new position behind the Chiusella River, close to the village of Romano, about ten miles south of Ivrea, joining strong forces under Hadik on 25 May. On the following day the French attacked again, and Lannes won the first major victory of the campaign (battle of Romano-Chiusella)