Mace joined the army on October 21, 1915. On July 22 1917, he transferred from an artillery regiment to the French Air Service. After flight training he received a Pilot's Brevet, and was assigned to Spa90 where he credited for shooting down four enemy aircraft and eight balloons by the war's end.

Médaille Militaire
"Self-sacrificing, audacious, and unselfish pilot who is an excellent example to all. He has returned sixteen times with his clothes and aircraft shot through by enemy fire. He has destroyed two planes and one balloon. On September 22, 1918, he reported two new victories by flaming two enemy observation balloons. Four citations." Médaille Militaire citation