Cunningham attended the Midland Army Flying School in Midland, Texas. He graduated from Bombardier School in 1942. At the time, Midland Army Flying School was the largest bombardier school in the world. He was a second lieutenant at this point and was awarded Mississippi honors at his graduation.
Harold was a First Lieutenant of the 424 Bomber Squadron of the 307 Bomber Group in the U.S. Army Air Forces.