Owen Monaghan pronounced his vows as a Passionist Religinus on August 1, 1928, and was ordained a Catholic Priest on June 6, 1936, by the Most Reverend Gerald T. Bergan, Bishop of Des Moines, at Saint Ambrose Cathedral. He initially served as a priest at Saint Gabriel Passionist Monastery, Des Moines, Iowa, and left there in 1942 to enlist in the Army as a chaplain. He went overseas the following December, serving in the South Pacific, first with the 41st Infantry Division where he earned a Silver Star in 1943. Two years later, while serving with the 32d Infantry Division, he was killed in action at Luzon, Philippine Islands.