Joseph O’Callahan graduated from Boston College High School and then joined the Jesuit Order in 1988. He completed philosophical studies at Weston College in 1929, and began teaching Physics at Boston College. He was ordained a Catholic Priest in 1924, and became director of the Mathematics Department at Holy Cross College, Worcester, Massachusetts. He subsequently earned his Master of Arts, Doctor of Philosophy, and Licentiate in Sacred Theology from Georgetown University in Washington, D.C. He was teaching math, physics, and philosophy at Holy Cross when he requested permission to enter military service as a U.S. Navy Chaplain in 1940. In 1942 he was assigned to the U.S.S. Ranger (CV-4), an aircraft carrier in the Atlantic Fleet, and after that to the U.S.S. Franklin. He was the first chaplain since the Civil War, and the first Catholic Chaplain in history, to earn the Medal of Honor. He was released from active duty on November 12, 1946, with the rank of full commander, and remained in the Naval Reserve until 1953, retiring as a captain. He returned to Holy Cross, but suffered a disabling stroke and retired from teaching in 1950. He wrote about his experiences in the book “”I Was Chaplain on the Franklin.”