Сен-Сир
Debax was born in Toulouse on 28 September 1864 at 21:00. He was the son of Gervais Achille Francois Alexandre Debax and Blanche Chemineau Debax. Debax joined the French Army in Toulouse on 24 October 1882, for an initial five-year commission, and seven days later became an officer cadet at the Ecole Spéciale Militaire de Saint-Cyr. He was promoted to corporal-cadet on 3 November 1883 and was commissioned as a sub-lieutenant in the 83rd Infantry Regiment on 1 October 1884. Debax was promoted to lieutenant in the 57th Infantry regiment on 29 February 1888.