Father O’Callahan was a good Boston boy. Shortly after he graduated from high school in 1922, he signed up with the Jesuits.
He was ordained as a Jesuit priest in 1934. Along the way, he picked up a BA and a MA from St. Andrew’s College, “specializing in mathematics and physics”. He was a professor of math, physics, and philosophy at Boston College for 10 years (1927-1937), then he went over to Weston Jesuit School of Theology for a year. From 1938 to 1940 he served as the director of the math department at the College of the Holy Cross.
He enlisted in the United States Navy Reserve Chaplain Corps in August of 1940 as a lieutenant junior grade. But I gather he was pretty good at his job: by July of 1945 he had reached the rank of commander. He participated in Operation Torch and Operation Leader.
On March 2, 1945, Commander O’Callahan reported to the aircraft carrier USS Franklin.
On March 19, 1945, the Franklin was hit by two bombs from a Japanese aircraft. The bombs started a massive fire on the carrier deck.
There is a short documentary, “The Saga of the Franklin“, that you can find on the Internet Archive.
Commander O’Callahan was offered the Navy Cross, but refused it. There is speculation that his refusal had to do with “his heroic actions on USS Franklin highlighted perceived lapses in leadership by the ship’s commanding officer, Captain Leslie E. Gehres, which reflected poorly on the Navy”. Wikipedia claims there was a controversy at the time, Harry Truman stepped in…
…and Commander O’Callahan was awarded the Medal of Honor on January 23, 1946. (Another officer, Lieutenant junior grade Donald Arthur Gary, also received the Medal of Honor for his actions: “Lieutenant Gary discovered 300 men trapped in a blackened mess compartment and, finding an exit, returned repeatedly to lead groups to safety. Gary later organized and led firefighting parties to battle the inferno on the hangar deck and entered number three fireroom to raise steam in one boiler, braving extreme hazards in so doing.“)
Father O’Callahan retired from the Navy in 1948 and headed the math department at The College of the Holy Cross. He also wrote a book, I Was Chaplain on the Franklin (affiliate link).
He died in 1964 at the age of 58, and is buried in the Jesuit cemetery at The College of the Holy Cross. The destroyer USS O’Callahan was named after him.
One of Father O’Callahan’s students at Holy Cross before the war was John V. Power, who also received the Medal of Honor (posthumously).
(Previously. Previously.)