The first American pilot credited with five victories in a single engagement, Simon joined the Royal Flying Corps in March of 1918. Assigned to 139 Squadron under William Barker, he was flying the Bristol Fighter on the Italian Front when he and his observer shot down five enemy aircraft on the morning of July 30, 1918.

Immediately following the war, Simon left London for Lima, Peru where he was responsible for training pilots to fly surplus Bristol Fighters and played an instrumental role in the formation of the Peruvian Air Force for president Augusto B. Leguia's controversial government.

Distinguished Flying Cross (DFC)
"This officer has carried out sixteen successful reconnaissances, many at long distances, and frequently strongly opposed by hostile aircraft. In this service, Lt. Simon has shown great ability and determination, rendering excellent reports and obtaining much valuable information. In the encounters with hostile aircraft, he has proved himself a gallant and skilful fighter." DFC citation, London Gazette, November 2, 1918