Jacquet entered the Military Academy in October 1907. After serving as an infantry officer, he received a pilot's brevet on February 25, 1913 and made his first flights with 2me Escadrille. Despite less than perfect vision, he was assigned to 1ère Escadrille in 1915. Claiming an Aviatik C over Beerst on April 17, 1915, Jacquet was the first Belgian pilot to score an a victory.

In December of 1916, he assumed command of 1me Escadrille and was the first pilot to fly King Albert to the front in 1917. Jacquet was promoted to Capitaine-Commandant in December of 1917 and three months later, at the request of the King, he assumed command of the newly formed Belgian Groupe de Chasse. Scoring most of his victories from the cockpits of Farmans, Jacquet also flew the Sopwith 1½ Strutter and SPAD S.XI in combat. Discharged from the army in 1920, he was the only Belgian pilot to receive Britain's Distinguished Flying Cross. In 1921, he opened a flying school at Gosselies and during World War II, Jacquet served with resistance until his capture by the Germans in 1942.