Louis de Ghaisnes was born at the castle Bourmont (Anjou) on September 2, 1773, into a noble family. He emigrated during the French Revolution and served in 1792 and 1793 in the army of Condé and the army of the Princes. He passed in the Vendée in February 1795.
In the following years, he acted as an agitator and a royalist liaison officer.
In 1799, Bourmont was one of the leaders of the new Vendée insurrection. He took Le Mans on October 15, signed peace in January 1800 but resumed his work as a conspirator. He dipped in all the royalist plots of the Consulate.
Arrested, he was incarcerated in the Temple Jailhouse in Paris, then in Besançon, where he escaped in 1804.
After the capitulation of Cintra (August 30, 1808), Bourmont returned to France where he was immediately arrested. He was released by Junot.
He joined the Bourbons in 1814, but offered his services to the Emperor during the Hundred Days. Napoleon gave him the command of a division. However three days before the Battle of Waterloo, he organized collective desertion of his staff.
After the Restoration, his testimony contributed to the death sentence of Marshal Ney.
He was made Peer of France in 1823. In 1829, the Ministry of War was proposed to him, but that offer provoked a wave of protests and resignations in the army.
He got in return the command of the expedition to Algiers. The city ffell on July 5, 1830 and Bourmont was appointed Marshal of France.
After the French revolution of 1830, he took refuge in England. In 1832, he tried to rekindle the civil war in the Vendee, and was deprived of French nationality.
He was pardoned in 1840 and returned in France where he died on October 27, 1846.