Promoted to a General on 25 June 1778, La Rouërie took part in the battles of New York, Monmouth, Short Hills, Brandywine, Whitemarsh, the Campaign in Virginia, and the Siege of Yorktown. In 1781, Colonel Armand returned to France to re-equip his troops, and was there made a Knight of the Order of Saint-Louis. On 26 March 1783, he was made a Brigadier General in the American Army, though he left the American Army on 25 November that year. He returned to France in the summer of 1784. He retained his friendship with Washington after leaving America and the two continued to correspond. La Rouërie was also made a member of the Society of the Cincinnatis French chapter.