He is considered an apostle to Africa, and the founder of the Abyssinian mission. Blessed Ghebre Michael , CM is among the estimated 12,000 converts he made in his time. He is also considered the founder of a new Catholic generation and formator of its native clergy.
See especially St Justin de Jacobis: Founder of the New Catholic Generation and Formator of its Native Clergy in the Catholic Church of Eritrea and Ethiopia by Abba lyob Ghebresellasie, C.M.
Vincentian Encyclopedia entry Justin deJacobis