When old enough, McEvoy joined the
Royal Flying Corps. In January 1918, he was assigned to No. 66 Squadron in Italy as a pilot. He was slightly wounded the following month, and hospitalized for a short while. On 30 March 1918, he scored his first aerial victory; by 1 August, he had run his tally of victories to nine. Illness then removed him from the cockpit; he was medically evacuated back to England with
dysentery. After recovery, he served in No. 37(Home Defence) Squadron. He was awarded
Distinguished Flying Cross, gazetted on 23 September 1918: ==List of aerial victories==