Joseph Timothy O'Callahan (May 14, 1905 – March 18, 1964) was a Jesuit priest and, during World War II, a United States Navy chaplain. He was awarded the U.S. military's highest decoration, the Medal of Honor, for his actions during and after an attack on the aircraft carrier aboard which he was serving, . Early years and career O'Callahan was born on May 14, 1905, in the Roxbury neighborhood of Boston, Massachusetts. He joined the Society of Jesus (Jesuits) in 1922, shortly after graduating from Boston College High School. He began the 13 years of training required of a Jesuit at St. Andrew's College, Poughkeepsie, New York, where he received the Bachelor of Arts degree in 1925 and his Master of Arts degree in 1929, specializing in mathematics and physics in addition to religious philosophy. He was ordained to the Roman Catholic priesthood as a member of the Jesuit order in 1934. He was a professor of mathematics, philosophy, and physics at Boston College from 1927 to 1937. He then spent a year (1937–1938) as a professor of philosophy at Weston Jesuit School of Theology (Weston College). He served as the director of the Mathematics Department at the College of the Holy Cross, Worcester, Massachusetts from 1938 to 1940. Among his students at Holy Cross was John V. Power, who would himself be awarded the Medal of Honor, although posthumously, during World War II. After the war, while O'Callahan was a patient at Saint Vincent Hospital, he was tended to by Power's sister, Patricia Power Rose, a nurse. Military service Appointed lieutenant (junior grade) in the Chaplain Corps of the U.S. Navy Reserve on August 7, 1940, Chaplain O'Callahan advanced progressively in rank and attained that of commander in July 1945. His first assignment at sea was on , participating in Operation Torch off North Africa in 1942 and Operation Leader off Norway in 1943. While in active service, O'Callahan reported aboard USS Franklin on March 2, 1945. 17 days later, the ship was severely damaged at dawn by two bombs from a lone Japanese aircraft. The hangar deck immediately became an inferno of exploding gas tanks and ammunition. Although wounded by one of the explosions after the attack, Chaplain O'Callahan moved about the exposed and slanting flight deck, administering the last rites to the dying, comforting the wounded, and leading officers and crewmen into the flames to carry hot