Hilary of Poitiers, Bishop, 367
Keep us steadfast, Lord God, in that true faith that we professed at our baptism; that, like your servant Hilary of Poitiers, we may rejoice in having you for our Father, and may abide in your Son, in the fellowship of the Holy Spirit; for you live and reign for ever and ever as one God in Trinity of Persons. Amen.
Hilary of Poitiers (315-367) lived during the great controversy between Athanasius, who taught that the Son is fully God, equally with the Father, and Arius, who denied this.
Hilary is sometimes called "the Athanasius of the West." He was bishop of Poitiers, and when he refused to sign a condemnation of Athanasius, the Arian emperor Constantius (one of the sons of Constantine) banished him to Phrygia in 357. His exile lasted three years, during which time he wrote several essays, including On the Trinity. Finally the Emperor was forced to send him back to Gaul because he was causing such difficulties for the Arians in the East. In 364, he journeyed to Milan, where he engaged in public debate with the Arian bishop Auxentius, and persuaded him of the error of his ways. *
* The Lectionary, James Kiefer, http://satucket.com/lectionary/Hilary.htm