His proximity to the Carmelite community profoundly influenced his future, and he left Kinsale to enroll in the Carmelite-run Terenure College in Dublin.

His first academic appointment was to the Professorship of Moral Theology at the International College of Saint Albert, a house of studies for Carmelite students in Rome.

[2] From October, 1943, Pope Pius XII asked churches, convents and other Catholic institutions throughout Italy to shelter Jews from persecution.

[3] Leahy responded, at personal risk to himself, by hiding the Jewish owner of a nearby and well-known restaurant, Scoglio di Frisio.

Father Leahy wrote two books on Mother Marie Joseph Butler (1860-1940) under the pseudonym, Carmelite Pilgrim:[9]