Commandant of the 1st Infantry Division of expeditionary corps to Mexico on 1 July 1862, his action was decisive during the siege of Puebla in 1863. He commanded with great distinction the First Division under General (afterwards Marshal) Forey in the Mexican expedition in 1862, where he pursued the war with great vigour and success, driving President Benito Juárez to the frontier. His decisive action was instrumental in the taking of the city of Puebla in 1863. As a consequence, he was cited and designated at the head of the expeditionary corps by replacing Élie Frédéric Forey. He received a citation at the battle of San Lorenzo and the insignias of the Grand-Croix of the Légion d'honneur, on 2 July 1863. He was elevated to the dignity of Marshal of France and Senator () of the Second French Empire by Imperial decree on 5 September 1864, the first Marshal who had started as a Legionnaire. He commanded in person the siege of Oaxaca in February 1865, following which, the Emperor complimented him while decorating him with the Médaille militaire, on 28 April 1865.