Following the United States' entry into World War I in April 1917, Frank enlisted in the Aviation Section, U.S. Signal Corps on September 25, 1917. After being commissioned as a second lieutenant in March 1918, he deployed to France and was assigned to the 27th Aero Squadron. The 27th was under orders to destroy German observation balloons. Because of this, Luke, along with his close friend Lt. Joseph Frank Wehner, continually volunteered to attack these important targets although they were heavily defended by anti-aircraft guns on the ground. The two pilots began a string of victories together, with Luke assaulting the balloons and Wehner as his wingman.
Between Sept 12 and Sept 29, Luke was credited with shooting down 14 German balloons and 4 airplanes. Luke achieved 18 victories in 8 days, a feat unsurpassed by any pilot in World War I. He passed away after a crash landing behind enemy lines on September 29, 1918.
Frank was credited with 19 aerial victories, ranking him 2nd among United States Army Air Service pilots after Captain Eddie Rickenbacker. He was the first airman to receive the Medal of Honor and the first USAAS ace in day. Luke Air Force Base, Arizona, a United States Air Force pilot training installation since World War II, is named in his honor.