The combat of Sassuolo (23 June 1799) was a second French rearguard action (after the combat of San-Giorgio of 20 June) fought after the French defeat on the Trebbia on 17-19 June.
After suffering defeat on the Trebbia General Macdonald had retreated east to the River Nura, where his left wing (under General Victor), fought a rear-guard action at San-Giorgio. The French continued to retreat east, reaching the Secchia, another of the rivers that flow north from the Apennines to the Po. Macdonald's aim was to cross the Apennines and then move west along the coast to join up with General Moreau at Genoa.
The key to the French position was at Sassuolo, just to the south-west of Modena. If the Austro-Russians under Marshal Suvarov could force their way across the river at this position then they could prevent Macdonald from reaching the crucial passes.
Macdonald posted General Calvin's brigade at Sassuolo, and then ordered General Lacroix to join him. Suvarov sent General Ott, with his own and General Klenau's divisions, to attack this position.
At first the Allies were successful. Calvin retreated without a fight, and Sassuolo fell. Lacroix then arrived on the scene, and managed to retake Sassuolo, taking 600 prisoners and stopping the Allied pursuit.
In the aftermath of this success the French were able to continue their retreat. Macdonald reinforced the garrisons of Bologna and Urbino, and then moved south to Pistoia and Lucca. At the same time General Victor, now commanding the French rearguard which was still some way to the west, advanced up the Taro valley to join with General Lapoype's division. Their combined force was able to hold the mountain passes, and prevent the Austro-Russians from reaching the coast. Macdonald was able to advance west from Lucca to Sarzana, La Spezia and Sestri Levante to join up with Moreau at Genoa.