He served in
Escadrille MS.26 as an
aerial observer in
Morane-Saulniers. He then passed through pilot's training, being brevetted a pilot on 29 May 1915. He was assigned to
Escadrille MS38, another Morane-Saulnier squadron. He was promoted to lieutenant on Christmas Day, 1915. On 5 June 1916, he transferred to a fighter squadron,
Escadrille N3, to fly
Nieuports. Later, he assumed command of the unit. Another would entail merging his
escadrille with three others to form the world's first fighter wing,
Groupe de Combat 12 on 16 October 1916. GC 12 would be better known by its nickname,
Les Cigognes (the Storks) for the bird portrayed on their planes. He scored for the first time on 9 July 1916. Following victories on 16 July, 2 and 3 August, He was flying a new
Spad S.VII when he downed his fifth victim on 17 August 1916. Later the next month, on the 25th of September, he shot down another pioneer ace,
Leutnant Kurt Wintgens, the very first fighter pilot to ever score a victory on July 1, 1915, with a synchronized machine-gun armed aircraft; for victory number eight. He continued to accumulate victories steadily over the next eight months, reaching 21 on 4 May 1917. On 5 May 1917, he was seriously wounded In a dogfight with nine
Albatros D.IIIs, he was hit through both cheeks and both thighs, as well as his head being grazed by a near-miss. He eventually returned to duty, but did not score again. A second serious wounding in September 1917 sidelined him for the remainder of the war. When he recovered, he toured the
United States of America lecturing on fighter tactics. ==Between the world wars==