Altheus was a Catholic bishop and abbot who held significant religious and political influence during the late 8th and early 9th centuries. Serving as the Bishop of Sion and the abbot of Saint-Maurice-d'Agaune, he occupied strategic positions within the Valais region. Some historical traditions suggest he may have been a relative of Charlemagne, who entrusted him with these important leadership roles. His recorded activities include participating in the Council of Tegernsee in 804, which marks his final known historical appearance before his death around 824.
Life and career
Altheus succeeded Willicaire to hold his dual offices between approximately 786 and 788. His leadership of the Abbey of Saint-Maurice and the Church of Sion provided the Frankish empire with a vital strategic foothold near the Lombard kingdom. While some traditions link him to the papacy through a disputed privilege from Hadrian I, his most certain historical presence is noted during the ecclesiastical council held in Tegernsee in June 804.
Veneration
The saint is commemorated on two different dates, with his feast day falling on March 13 at Saint-Maurice and September 23 in Sion. He remained a figure of devotion through the 18th and 19th centuries. A reliquary dedicated to the Virgin Mary, attributed to his commission, is preserved within the treasury of the Notre-Dame Cathedral in Sion.