Jean Dacier, Benedictine, was a licentiate in civil law and prior of Besson.

He was Abbot of Belfont in 1418 and Abbot of Saint Corneille in Compiègne after June 23, 1424.

He was completely acquired by the Burgundian party, as the notes of Dom Gilesson prove, which are preserved in a few copies of the ancient archives of Compiègne.

A former almoner of Pope Martin V, Jean Dacier died on May 4, 1437, after having been present at the Council of Bâle as representative of the abbeys of the province of Reims.
The abbey of Saint Corneille was in the heart of the city near the great market.