Formed in April of 1916 as the "Escadrille Américaine" (number 124) in Luxeuil prior to U.S. entry to the war, the squadron was quickly moved to Bar-le-Duc, closer to the front. A German objection filed with the U.S. government led to the name change in December.
The planes (mostly Nieuport 124s) and their mechanics, and the uniforms, were French, as was the commander, Captain Georges Thenault. Five additional French pilots were also on the roster, serving at various times.
The first major action seen by the squadron was at the Battle of Verdun. The squadron suffered heavy losses, but its core group of 38 was rapidly replenished by other Americans arriving from overseas. So many volunteered that a "Lafayette Flying Corps" was formed in part to take the overflow. Altogether 265 American volunteers served in the Corps. Its members included Eddie Rickenbacker and Jimmy Doolittle.
63 members died during the war, 51 of them in action against the enemy. The Corps is credited with 159 enemy kills. It amassed 31 Croix de Guerre, and its pilots won seven Médailles Militaire and four Légions d'Honneur. Eleven of its members were flying aces. The core squadron suffered nine losses and was credited with 57 kills.
The Escadrille had a reputation for daring, recklessness, and a party atmosphere; the officers' club was notorious. Two lion cubs, named "Whiskey" and "Soda", were made squadron mascots.
On February 8, 1918, the squadron was reorganized into the U.S. Army as the 103rd Pursuit Squadron. For a brief period it retained its planes and mechanics. Most of its veteran members were set to work training newly-arriving American pilots.