Joseph Timothy O'Callahan was born in Boston, Massachusetts, on 14 May 1905. He joined the Jesuit Order of the Roman Catholic Church in 1922, after graduation from preparatory school, and subsequently received degrees from several institutions of higher learning. He was ordained in 1934, and was a Professor of Mathematics, Philosophy and Physics at Boston College in 1929-37, Professor of Philosophy at the Jesuit Seminary of Weston College in 1937-38 and Director of the Mathematics Department at Holy Cross College, Worcester, Massachusetts, in 1938-40.
Father O'Callahan was commissioned as a Lieutenant (Junior Grade) in the Naval Reserve Chaplain Corps in August 1940. He was assigned to the Naval Air Station, Pensacola, Florida, in 1940-42, to the aircraft carrier Ranger in 1942-44 and to the Naval Air Stations at Alameda, California, and Pearl Harbor, Hawaii, into early 1945. Lieutenant Commander O'Callahan joined the the aircraft carrier Franklin in early March 1945. A few weeks later, when his ship was badly damaged by a Japanese air attack, he distinguished himself comforting the injured and leading damage control and ammunition jettisoning parties. The ship's Commanding Officer described O'Callahan as "the bravest man I ever saw". For his heroism on board Franklin, Lieutenant Commander O'Callahan was awarded the Medal of Honor.
Department and at the Naval Training Station, Newport, Rhode Island, until Promoted to the rank of Commander in July 1945, O'Callahan served at the NavyOctober 1945, when he reported on board the new aircraft carrier Franklin D. Roosevelt. In 1946, he served as Escort Chaplain as the body of the late Philippines President Manuel Quezon was carried from the United States to Manila. Released from active duty in November 1946, Commander O'Callahan returned to Holy Cross College as Professor of Philosophy. Upon his retirement from the Naval Reserve in November 1953, he was advanced to the rank of Captain on the basis of his combat awards. Joseph T. O'Callahan died at
Worcester, Massachusetts, on 18 March 1964.
On 21 July 1965, the USS O’CALLAHAN, a Destroyer Escort vessel, was christened in Bay City, Mich. Present at the ceremony was Sister Rose Marie, O.P., also known as Alice O’Callahan, Joseph’s younger sister, who had survived her own ordeal in the Philippines. The escort ship USS O'Callahan (DE-1051, later FF-1051), 1968-1994, was named in honor of Joseph T. O'Callahan.