After three years at the Ecole he was admitted into the corps of engineers, and served in the army of the Sambre and Meuse; he was present at the passage of the Rhine in 1797, and at the affairs of Ukratz and Altenkirch.
It is more commonly spoken of as being in the district entre Sambre et Meuse.
In 1794 we find him as brigadier attached to the army of the Sambre et Meuse, and after Jourdan's victory at Fleurus he was appointed a general of division.
The Gallo-Celtic tribes bore the general appellation of Belgae, and among these the Nervii, inhabiting the district between the Scheldt and the Sambre were at the date of Caesar's invasion, 57 B.C., the most warlike and important.
Gerard's corps (with which was Kellermann's cuirassier corps) halted astride the Sambre at Chatelet.
When he had left for the front, the emperor proceeded with Grouchy to reconnoitre the Prussian position at Gilly; and handing over the command of the right wing to the marshal, whom he ordered to capture Gilly, Napoleon returned to Charleroi, to hasten the passage of the French army across the Sambre and mass it in the gap between the allies.
The Goths across the Danube, passed beyond the Rhine and occupied north-eastern Gaul; Ripuarians of the Rhine establishing themselves on the Sambre and the Meuse, and Salians in Belgium, as far as the great fortified highroad from Bavai to Cologne.
When the French left wing and centre reached the Sambre bridges, at Marchienne and Charleroi, they found them held and strongly barricaded, and the cavalry were powerless to force the passage.