Ado of Vienne

Ado of Vienne, known in Latin as Ado Viennensis and in French as Adon de Vienne, was a ninth-century Frankish Benedictine monk, archbishop, and hagiographer, honoured as a saint in the Latin Church. He was born about the beginning of the ninth century into a family of the nobility in the diocese of Autun, in Burgundy. He was educated at the Benedictine abbey of Ferrières, a noted school of the Carolingian world in the Gâtinais, and there embraced the monastic life. Friction with members of the community—later writers attribute it to envy of his learning and austerity—led him to leave Ferrières. He found a welcome at the abbey of Prüm in the Ardennes, then under Abbot Markward, and remained there for some years as a monk and teacher.

In the later 850s Ado travelled to Italy. He spent time in Rome and afterwards in Ravenna. Medieval accounts relate that at Ravenna he obtained an old martyrological manuscript of Roman origin, which he used in compiling the calendar of saints later known as the Martyrologium Adonis. On his return to the Frankish kingdoms he was received by Archbishop Remigius of Lyons and served for a time in that diocese. After the death of Archbishop Agilmar of Vienne in 859, Ado was chosen to succeed him and was installed as archbishop about 860, receiving the pallium from Pope Nicholas I. As metropolitan he laboured for reform of clergy and monasteries, attended Frankish synods, and aligned himself with the papacy in the great disputes of the day, including the resistance to King Lothair II's effort to repudiate Queen Theutberga.

Ado's principal writings belong to history and hagiography. The Martyrologium that bears his name, organized day by day through the year, drew on the Hieronymian martyrology, Roman tradition, and Gallican cults; it was widely copied and became a major source for Usuard and for the later Roman Martyrology, though modern scholarship has shown that it also contains legendary notices and some historically unfounded assignments of saints to particular dates. He composed a world chronicle, the Chronicon or Breviarium de sex mundi aetatibus, running from Creation to 869, which later annalists used and continued. He also wrote lives of saints connected with his see, notably of Saint Desiderius (Didier) of Vienne. These works place him among the learned prelates of the later Carolingian renaissance, anxious to supply the Church with liturgical and historical texts modelled on Roman authority.

Ado died at Vienne on 16 December 875. He was venerated as a saint from an early date; his feast is observed on 16 December. Like most saints of the first millennium he was never the subject of a formal papal canonization of the later medieval type. He is remembered as a reforming archbishop of Vienne and as the compiler of a martyrology that helped fix the Western sanctoral cycle for centuries.