According to an ancient legend, he was one of the seventy-two disciples of Christ, and was sent to Gaul by Saint Peter as bishop, together with the deacon Valerius and the subdeacon Maternus, to preach the Gospel.

After founding many churches the three companions went to Trier where the work of evangelization progressed so rapidly that Eucharius chose that city for his episcopal residence.

The staff of St. Peter, with which he had been raised to life, was preserved at Cologne until the end of the 10th century when the upper half was presented to Trier, and was afterwards taken to Prague by Emperor Charles IV.

When at a later period the lives of primitive holy founders, e. g. the saints of ancient Trier, came to be written anew, the gaps in tradition were filled out with various combinations and fanciful legends.

Later criticism has detected many contradictions and inaccuracies in these ancient records, and it is almost universally believed at present that, with few exceptions, the first Christian missionaries came to Gaul, to which Trier then belonged, not earlier than about 250.

[3] Following Hontheim, Calmet and others, the Bollandists, with Marx, Aloys Lütolf, and other historians refer these bishops of Trier to a period following 250, though not all of them consider this as fully established.