A two-seater pilot throughout the war, Jacquet was the son of a wealthy landowner. He entered the Military Academy in October 1907. Despite less than perfect vision, after serving as an infantry officer he received a pilot's brevet on 25 February 1913. He made his first flights with 2me Escadrille de Chasse and was assigned to 1ère Escadrille in 1915. Inspired by Roland Garros, who had equipped a Morane monoplane with a machine gun, Jacquet fitted one to his Farman pusher. Claiming an Aviatik C over Beerst on 17 April 1915, Jacquet was the first Belgian pilot to score an aerial victory. In December 1916, he assumed command of 1me Escadrille and on 1 February 1917 he became Belgium's first ace, scoring all five victories flying the Maurice Farman. Jacquet was also the first pilot to fly King Albert to the front in 1917. Jacquet was promoted to Capitaine-Commandant in December 1917 and three months later, at the request of the King, he assumed command of the newly formed Belgian Groupe de Chasse. With the Groupe de Chasse, Jacquet flew the Sopwith 1½ Strutter and SPAD S.XI in combat. He was discharged from the army in 1920 and, in 1921, he opened a flying school at Gosselies. During World War II, Jacquet served with the resistance until his capture by the Germans in 1942.