Legend says that he was one of the 72 disciples of Christ, and that he was sent to Gaul as its first bishop in the 1st century. There, one of his companions, Maternus, died. Eucharius returned to Saint Peter the Apostle, borrowed his pastoral staff, returned to Gaul, touched Maternus with the staff, and brought him back to life.
New Catholic Dictionary Book of Saints, by the Monks of Ramsgate Our Sunday Visitor's Encyclopedia of Saints, by Matthew Bunson, Margaret Bunson, and Stephen Bunson