Born at Juvardeil, Anjou, he gained his first military experience in the American War of Independence, and on his return to France was made a captain of grenadiers in the French royal army. He was a staunch defender of the French monarchy, and at the outbreak of the Revolution, resigned his command and retired to his château at Saint-Florent-le-Vieil. In the spring of 1793 he was chosen leader by the insurgents of the Vendée, and his directives were largely responsible for the success of the peasants arms.
He was present at the taking of Bressuire, Thouars, and of Fontenay-le-Comte - where he was wounded. Dissensions among their leaders weakened the insurgents, and at the bloody battle of Cholet (October 1793) the Vendéans sustained a severe defeat and Bonchamps was mortally wounded. He died the next day.
It is said that his last act was the pardoning of five thousand Republican prisoners, whom his troops had sworn to kill in revenge for his death. A statue of him by Pierre Jean David stands in the church of Saint-Florent-le-Vieil.