Hardy was born on 19 May 1762 in Mouzon, a village that is now in the Ardennes department of France. He enlisted in an infantry unit at age 21. At the time of the French Revolution, he was a fourrier in the "Royal-Monsieur" Regiment with the brevet rank of sous-officer. He joined the "Epernay" Volunteers and fought at the Battle of Valmy on 20 September 1792, earning promotion to Chef de bataillon (major). He became the commander of the 7th Battalion of the "Marne" Volunteers, leading his unit at the Battle of Wattignies on 17 October 1793. In the following month he was assigned to hold Philippeville against the Austrians and his vigorous defense was crowned with success. Hardy was promoted general of brigade on 16 November 1793.