He frequently was assigned as aide-de-camp to generals Barthélemy Catherine Joubert and Louis-Alexandre Berthier, serving in the Italian campaigns.

[1] He tied close connections to the latter officer, eventually marrying his niece Josephine-Therese Virginie (1794–1833), a daughter of his brother César Berthier, in 1810.

In March 1804 he was awarded the Legion of Honour and a year later was named Colonel of the 23rd Mounted Chasseur Regiment.

He also became a part of the new military nobility in 1808, being made a Baron of the Empire, and eventually was named Commandant in the Legion.

In 1812 he commanded the 1st Light Cavalry Division of the Grande Armee during the ill-fated French invasion of Russia, collecting further distinction and war wounds.