Leclerc started his military career as a volunteer in the French Revolution and within two years had risen to a post of divisional chief of staff at the siege of Toulon. Following the revolutionary success there, he campaigned along the Rhine. He began serving under Napoleon Bonaparte in the Italian campaign and fought at Castiglione della Pescaia and Rivoli.
In 1797, the newly promoted General de Brigade Leclerc married Napoleon's younger sister Pauline Bonaparte, with whom he had a child.
After tenures in the Army of Ireland and the Army of England, Leclerc gained promotion to general de division, which allowed him to aide Napoleon Bonaparte's bid for power. He participated in the coup d'etat of 18 Brumaire in November 1799 making Napoleon the ruler and military dictator ("First Consul") of France. More military campaigns followed on the Rhine and in Portugal and then in 1802 his brother-in-law appointed him commander of the expedition to recover the former French colony of Saint-Domingue, now Haiti, where the French educated Toussaint L'Ouverture had mastered a virtually autonomous state.
The French won several victories after severe fighting; however use of brutality and deception to end the rebellion mired himself and his army in a quagmire. L’Ouverture was hence invited to an agreement negotiation. Acting on Napoleon’s surreptitious instructions, Leclerc seized L'Ouverture during a meeting and deported him to France where he died in a prison in 1803.
This treacherous act swung the tide inexorably against French hopes. The native insurgents, led by another two French educated locals Jean Jacques Dessalines and Henri Christophe, expelled the French, who were weakened by an epidemic of yellow fever. Leclerc died of the fever.
See also: History of Haiti