Born John Boyle, Cosmas Boyle grew up in Pittsburgh, Pennsylvania, and was educated at Epiphany School and Saint Mary’s High School, which were conducted by the Sisters of Mercy. In 1914 he went to the Passionist Preparatory College at Saint Joseph Monastery, Baltimore, Maryland. He professed his vows and had the religious name Regis. He studied at Saint Ann’s Monastery, Scranton, and Saint Michael’s Monastery, Hoboken, and was ordained a Catholic priest on June 13, 1933. He stayed in Baltimore for his year of Sacred Eloquence, and then served in a series of parish missions before he was assigned to the parish staff at Saint Joseph’s Monastery Church in Baltimore. In 1942 he was commissioned a U.S. Army chaplain and served initially with a Ranger unit during the 1942 assault on North Africa. He continued in service with the 1st Infantry Division through campaigns in Sicily and Southern Italy, and was made Port Chaplain at Leghorn, Italy. After the war, in 1946 he was re-assigned to Saint Joseph’s Monastery in Baltimore.