He was most notable for losing the Battle of Puebla in the early stages of the Second French intervention in Mexico (ultimately culminating in the Second Mexican Empire) although he would continue to have military command during France's war with Prussia.

He later became a captain in 1840 before he served first in Algeria in charge of the 3e chasseurs à pied, specialized light infantry sent to handle skirmishes in the country's rough terrain.

In 1855, at the Battle of Malakoff during the Crimean War, he commanded a brigade in 5th division of 2nd corps where they were pushed back in ferocious fighting against the Russians at the Bastion du Mat.

He established his headquarters in Orizaba where he won skirmishes with Mexican forces at the Acultzingo Summit taking the high ground and persuading them to withdraw, afterwards proclaiming victory and triumph back to the minister of war in Paris famously saying, "We have over the Mexicans such a superiority of race, organization, discipline, morality, and elevated spirits that I beg you to inform the emperor that, from this moment on and at the head of six thousand soldiers, I am the master of Mexico."

Lorencez retreated towards Orizaba under constant pursuit by Mexican forces although the skill and tactics of the army itself prevented a total route and in fact made the attempted siege useless.

Criticized by the emperor himself and disgraced, the general left Veracruz on 17 December 1862, denied his desires to stay and fight in charge of 2e division.

Back in France, Lorencez was made Grand Officier de la Légion d'Honneur in 1866, but still in disgrace, he was only inspector general from 1864-1870.

When the Franco-Prussian War broke out in 1870, Lorencez at first in charge of a garrison in Toulouse until the 56 aged general was transferred into command of a wartime division, similar in size, 6,000 men, to his previous army in Mexico.