Eusebius was the founder of the canons regular, priests living under a religious rule and dedicated to pastoral work. The canons regular was the immediate result of the rise of monasticism in the East, and St. Eusebius of Vercelli saw the possibilities of this new movement for the clergy. His example was imitated all over the West and brought about a renewal of clerical life. He was born in Sardinia and as a child was taken to Rome, where he became a member of the Roman clergy under Pope Julius. Consecrated for the see of Vercelli in 344, he gathered his clergy into a community life, founding also the dioceses of Turin and Embrun. In 355, he attended the Council of Milan as legate of Pope Liberius, which defended St. Athanasius against those Western bishops intimidated by the emperor. When Eusebius was ordered along with other bishops to condemn Athanasius, he refused, insisting instead that they all sign the Nicene Creed. When threatened by the emperor, Eusebius stood his ground and told the emperor he had no right interfering in Church matters.

In anger, the emperor sent Eusebius into exile in Palestine, where he was severely mistreated by the Arians. He was moved around from place to place and after his release by the Emperor Julian he consulted with Athanasius in Alexandria on the Arian crisis. Returning to Italy, he joined with St. Hilary of Poitiers in opposing the Arian bishop of Milan and returned to Vercelli amid the rejoicing of his people.

Eusebius is considered by many to be the author of the Athanasian Creed, and a copy of the Gospels written in his own hand is preserved in the cathedral at Vercelli. He died on August 1, 371, his courage in suffering for the faith inspiring other bishops to oppose the Arian heresy.

http://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2014-08-02