Ralph O'Neill was born on December 7, 1896, in San Francisco, California. He enlisted in the Aviation Section of the U.S. Army Signal Corps in August 1917, and after completing flight training he was assigned to the 147th Aero Squadron, deploying to France in February 1918. Lt O'Neill was credited with the destruction of 5 enemy aircraft in aerial combat between July and October 1918, and then returned to the U.S. at the end of the war. He was discharged from the Army Air Service on February 19, 1919, and later served as a General in the Mexican Air Force from August 1920 to December 1925. During this time he trained pilots in the Mexican Air Force and flew combat missions during various rebellions in that country. Ralph later founded the New York, Rio, and Buenos Aires Line, an airline which operated in the late 1920's before merging with Pan Am in 1930. He died on October 23, 1980.

His 3rd Distinguished Service Cross Citation reads:

The Distinguished Service Cross is presented to Ralph Ambrose O'Neill, First Lieutenant (Air Service), U.S. Army, for extraordinary heroism in action near Fresnes, France, July 24, 1918: Lieutenant O'Neill, with four other pilots, engaged 12 enemy planes discovered hiding in the sun. Leading the way to an advantageous position by a series of bold and skillful maneuvers. Lieutenant O'Neill shot down the leader of the hostile formation. The other German planes then closed in on him, but he climbed to a position of vantage above them and returned to the fight and drove down another plane. In this encounter he not only defeated his opponents in spite of overwhelming odds against him, but also enabled the reconnaissance plane to carry on its work unmolested.