Having been promoted to Brigadier General on 21 July 1809, Lhéritier left his regiment the next day and was given command of the 2nd Brigade of the 3rd Heavy Cavalry Division. His command included the 7th and 8th Cuirassiers, but his brigade saw no action, as an armistice had been signed at Znaim on 12 July and the two parties were moving towards signing a peace treaty. The War of the Fifth Coalition ended on 14 October 1809 and General Lhéritier was discharged from his position on 1 May 1810. For almost a year, he was not given any assignment, but, on 26 March 1811, he was named inspector of the cavalry depots of the 1st, 15th, 21st and 22nd military divisions, then inspector of the remounts for the 2nd, 3rd, 4th and 5th military divisions (7 May 1811). He was subsequently given a field command, as he was placed at the helm of the 2nd brigade of General Jean-Pierre Doumerc's 3rd Heavy Cavalry Division (7 May 1811). During the upcoming French Invasion of Russia, General Lhéritier's brigade was noted for fighting with distinction at the Second Battle of Polotsk on 18–20 October 1812, but by then the outcome of the campaign had already been sealed and the remains of the once mighty Grande Armée pulled out of Russia.