AGEN, DIOCESE of. — City of southern France in Languedoc, situated on the Garonne River at its confluence with the Masse; it is the ancient Aginum and today has 27,500 inhabitants. It was once the capital of the Civitas Agennemium and later the capital of the kingdom of the Nitiobriges, which disappeared with the Roman conquest. It is not known precisely when Christianity was introduced there. Around the middle of the 4th century, the Church of A. is illuminated by St. Febadius (v.). He was already bishop of A. when he wrote his Liber contra Ariano, in 357, and after being among the principal participants in the Council of Rimini in 359, presided over those of Valence in 374 and Saragossa in 380. A. takes pride in counting among its priests the man who was called the Christian Sallust, Sulpicius Severus (v.). Occupied by the Visigoths from 412 to 507, and devastated by the Saracens and finally by the Normans in 848, A. rose from its ruins in 912 and experienced a flourishing of monastic institutions, despite the conflicts caused by heresy. It was under the rule of the kings of England, particularly from 1360 to 1463, and was annexed to the Crown of France in 1615. It is renowned for its beautiful church of S. Caprasio, in 12th–13th-century Gothic style.
The diocese, which following the Concordat of 1801 had absorbed the suppressed diocese of Auch and part of that of Montauban, has as its territory the department of Lot-et-Garonne (5,383 sq km and 247,500 inhabitants) and has 200,000 Catholics, distributed among 440 parishes administered by 263 priests. It currently belongs to the metropolitan province of Bordeaux, after having been united with that of Toulouse from 1802 to 1823.