The battle of Fombio (7-9 May 1796) was a small scale engagement fought as Napoleon's army crossed the River Po. In April Napoleon had won a series of victories that had forced Piedmont to sue for peace. This left him facing an Austrian army under General Beaulieu, which was defending the line of the River Po. The main Austrian defences were at the western end of the river, where most previous invaders had crossed, with a strong point at Pavia. Napoleon realised this, and decided to cross the river further east, at Piacenza. This would allow him to outflank the Austrian defences. At the very least Beaulieu would be forced to abandon Milan, but if all went well then the entire Austrian army could have been trapped.
Late on 6 May Napoleon issued his instructions for the march east along the south bank of the Po. Dallemagne was to take the lead, and would reach Piacenza on the next day. Leharpe was to reach Candelasco, five miles to the west. Augereau was to reach Castello San Giovanni, ten miles further west, and Masséna was to take up the rear at Voghera.
Napoleon accompanied the advance party, and personally supervised the first crossing of the Po. A small advance guard under Lannes was sent across in boats, driving away a small force of 150 Neapolitan horsemen. Over the next two days the rest of the French army followed them across.
When Beaulieu realised what was happening he abandoned his positions around Valenza and marched east to join General Liptay, who was holding the village of Fombio, just to the north of the Po. This position protected the most direct line of retreat from Valenza to Cremona, but on 8 May Generals Lannes and Dallemagne drove Liptay out of the village. The Austrians pulled back, leaving a rearguard in Codogno, to the north eat of Fombio.
On the night of 8-9 May a French force under General Leharpe occupied Codogno. On the morning of 9 May General Schubriz, commanding the Austrian advance guard, reached Codogno. Leharpe was killed by accident by his own men while returning to their camp, and the French were driven out of the village. For a short time the French were vulnerable, but Berthier and Dallemagne managed to drive Schubriz out of Codogno before Beaulieu could reach the scene. By the end of the day Masséna and Augereau's divisions were both across the river and had united at Casalpusterlengo. Beaulieu was forced to turn north to cross the Adda at Lodi, where on the following day Napoleon won one of his most famous victories.