During 1943, he was sent back to the United States to become a P-38 instructor in California. He completed 72 combat missions and 208 flying hours with the 1st Fighter Group. He was promoted to captain on April 5, 1943. In the spring of 1944, he was posted as squadron commander of the 79th Fighter Squadron of the 20th Fighter Group, the famous "Loco Busters", where Ilfrey was known for his fearlessness. He flew a P-38J-15-LO, serial number 43-28431, nicknamed "Happy Jack's Go Buggy." On May 24, 1944, he scored two more confirmed aerial victories on a mission over Berlin, Germany; one of them by ramming. A Messerschmitt Bf 109 collided with the right wing of Ilfrey's P-38 during aerial combat maneuvers, tearing off four to five feet of the wing tip; the German plane crashed, but Ilfrey managed to return to base in England. On June 13, 1944, after attacking the La Possonniere (Maine-et-Loire) railway bridge, he saw a locomotive at the Lion-d'Angers station. While attacking this objective, his aircraft was hit by anti-aircraft artillery fire. One of his engines caught fire and he parachuted, landing heavily on a farm building, his parachute having opened too low. Ilfrey was deep behind enemy lines. He was taken in by a friendly French family, who gave him shelter, food, a bicycle, and false identity papers as a deaf-mute farmer named "Jacques Robert." He eventually reached the Allied front line, and on June 20, 1944, he was back in England. After his escape, instead of being returned to the United States as most other evaders were (to prevent the enemy from extracting valuable information about resistance networks from them if they were captured again), Ilfrey returned to the 79th Fighter Squadron which was converting to P-51 Mustangs. He flew P-51D-5-NA 44-13761, obligatorily nicknamed "Happy Jack's Go Buggy." In early December 1944, his tour ended and he returned to the United States. He completed 70 combat missions and 320 flying hours with the 20th Fighter Group. Ilfrey spent the rest of the war in a staff position on the Pacific coast. He was discharged on December 28, 1945, with the rank of major. His final tally was seven and a half confirmed aerial victories, with two enemy aircraft damaged.