Trésain was a 6th-century Irish priest and missionary who traveled to France to preach. Born to prosperous parents in Ireland, he was joined in his mission by several siblings, including six brothers and three sisters, all of whom were recognized as saints. After studying Christian works and Latin, he was ordained by Saint Remy, the Archbishop of Reims, despite local opposition from the nobility. He spent his ministry serving the community in the Champagne region near the Marne river.