c.534 ? - 615
Irish Missionary

Columban was one of the greatest missionaries of the Celtic Church.

He established numerous monasteries in Ireland, England and Italy. Columban left Ireland (c.590) with 12 monks, including Attala, and St.Gall, and established himself in Gaul. He advocated the independence of the monastic movement from the Church and was indicted before a synod of French bishops.

Columban went with St.Gall to Switzerland, where he preached to the Alemanni, a pagan Germanic people. Compelled to leave, he went to Italy and founded the monastery of Bobbio.

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From the Catholic Encyclopedia:

Rule of St.Columban