Paul Mongillo was born on January 22, 1933, in Riverside, New Jersey. He enlisted in the U.S. Air Force on June 26, 1950, and was trained as a Radio Maintenance Technician before serving in West Germany from May 1951 to April 1954. Mongillo was promoted to TSgt (E-6) before attending Officer Training School at Lackland, AFB, Texas, where he was commissioned a 2d Lt on June 21, 1957. He then completed Undergraduate Navigator Training at Harlingen AFB, Texas, in May 1958, followed by Electronic Warfare Officer Training at Keesler AFB, Mississippi, in January 1959. His next assignment was as an Electronic Warfare Officer with the Chicago Air Defense Sector at Truax Field, Wisconsin, from February 1959 to September 1962, and then with the 30th Air Division at Truax Field from September 1962 to June 1963. Capt Mongillo served as an Electronic Warfare Officer on a specially modified C-97G Stratocruiser with the 7405th Support Squadron at Wiesbaden AB, West Germany, from June 1963 to June 1967. The mission of these aircraft was to provide photographic reconnaissance and electronic intelligence along the air corridors from West Germany to Berlin. Maj Mongillo then returned to the U.S., where he completed Air Force Survival Training in July 1967, and the Wild Weasel Course in October 1967, before deploying to Southeast Asia as an F-105G Wild Weasel Electronic Warfare Officer with the 44th Tactical Fighter Squadron at Korat Royal Thai AFB, Thailand, from November 1967 until he was killed in action during a mission over North Vietnam on December 16-17, 1967. He was critically injured from flak that hit the aircraft on his last mission on December 16, and died the next day. His remains were returned to the U.S. and he was buried at Beverly National Cemetery in Beverly, New Jersey.

His Air Force Cross Citation reads:

The President of the United States of America, authorized by Title 10, Section 8742, United States Code, takes pride in presenting the Air Force Cross (Posthumously) to Major Paul John Mongillo, United States Air Force (Reserve), for extraordinary heroism in military operations against an opposing armed force as an F-105 Thunderchief Electronics Warfare Officer of the 44th Tactical Fighter Squadron, Korat Royal Thai Air Base, Thailand, in action against an isolated vital military target near Hanoi, North Vietnam, on 16 December 1967. On that date, Major Mongillo braved many concentrations of heavy anti-aircraft artillery fire and eighteen surface-to-air missiles as he successfully led his missile suppression flight in diverting the hostile defenses away from the main strike force. He contributed to the destruction of one missile site only three miles from the center of the heavily defended target area and damaged at least one other missile complex. As a result of his actions, the main strike force suffered no losses, encountered only four missiles, and successfully destroyed this vital military target. Through his extraordinary heroism, superb airmanship, and aggressiveness in the face of hostile forces, Major Mongillo reflected the highest credit upon himself and the United States Air Force.