Liber rubeus de l'évêché d'Aire

Rediscovered by chance in 2002, the “Red Book” of the bishopric of Aire-sur-l’Adour – long thought lost since the French Revolution – is now preserved in the Departmental Archives of the Landes. Valuable not only for its content but also for the quality of its writing and ornamentation, this manuscript was compiled around 1335 during the episcopate of Garsie du Fau. It served as an essential tool for governance and administration, both spiritual and temporal, for its patron and the diocesan administration.

In addition to several excerpts from synods and councils, the manuscript notably contains the full text of the 1299 synod, previously unknown to scholars and researchers. Its forty recorded acts, dating from 1141 to 1501, also shed light on the organization of the diocese (pouillé), and on the often contentious – even violent – relationships between the bishop, regular religious houses, and lay lords, particularly in matters of tithe collection and ecclesiastical patronage.