When
World War I broke out, his father and stepmother moved to
London, England. However, Chapman decided to stay in France, joining the
French Foreign Legion on August 30, 1914, and served in the 3rd March regiment of the Legion. He became friendly with four men during his days in the trenches: a
Polish fighter who was known only as "Kohl", and Americans
Alan Seeger, Henry Fansworth, and David King. The trio of Americans watched as Kohl was killed by a bullet while walking with his friends. He was also friends with
Edmond Genet. After Kohl's death, Chapman and two other friends, (
Norman Prince and Elliot Cowdin), were given an opportunity to fly in a fighter
airplane. Chapman requested a transfer to the
Aéronautique Militaire, the army's air arm. He attended flight school and was certified as a pilot. Chapman flew many missions for the 1st Aviation Group and was promoted to sergeant. He was chosen as one of the founding members of N.124, the Escadrille Americaine, also known as the
Lafayette Escadrille. On June 17, 1916, he was flying over the
Verdun sector when he was attacked by four German aircraft. During the engagement, Chapman suffered a head wound, most likely from an attack by then four-victory German flier
Walter Höhndorf. Chapman landed his aircraft safely, with Höhndorf getting his fifth victory as a result. While recovering Chapman found out that his friend, Clyde Balsley had been wounded in a separate incident. Prior to his last flight Chapman loaded oranges onto his aircraft, intending to take these to Balsley who was in the hospital recuperating from his wounds. On June 24, 1916, while en route to Balsley, Chapman was again attacked, north of
Douaumont by German flying ace
Leutnant Kurt Wintgens, a close friend of Höhndorf. With Wintgens flying a
Halberstadt D.II that day against Chapman's Nieuport 11, Wintgens soon gained the upper hand and Chapman was shot down and killed. A memorial service was held on the 4th of July for Chapman. The service, which was held at the
American Church in Paris, included many of the American ambassador to France, American residents of Paris and any American soldiers in France that could make it. ==Awards and medals==