Missionaries in the Valais
Long before seeing its own people leave to evangelise far-off lands, the territory of the Valais (in its present form) underwent the influence of missionaries originating in the lower Rhone Valley, in particular Lyons and Vienne, who passed through the Chablais or the Great St. Bernard Pass to christianise the originally Celtic populations. A Roman inscription dated 377 and displaying a Christ monogram is generally considered to be the oldest testimony of the arrival of Christianity in the Valais. The presence of a first diocese in Octodurus (Martigny) is attested as early as 381, then of a cathedral. This first episcopal seat, which was removed to Sion two centuries later, constituted the advanced outpost on the strategic axis of the Roman road from which the work of converting the Valais regions was to be organized. The Abbey of Saint-Maurice was founded in 515 by a future Burgundian king at a pilgrimage site and gave its name to the neighbouring town. The abbey was a key stronghold in the project of the expansion of Christianity and it developed within the context of territorial wars. Its land holdings, seigneurial rights and missions were protected alternately by the kingdom of the Franks, the dukes of Burgundy and Savoy, then starting in 1571 by the Diocese of Sion and the Sept Dizains. The end of the Christian conquest of the Valais can be dated to around the 10th century, when almost all the localities of the upper Rhone Valley and side valleys were affiliated with parishes, which in turn were attached to the diocese.
Catholic dominance in the Valais was not self-evident. Under the influence of the Reformation that spread through the north of Europe, many noble families of the Valais converted to Protestantism as early as the 1520s, yet without necessarily calling the spiritual power of the Diocese into question. These conversions were motivated primarily by political considerations, in a context in which the nobles sought to protect their interests vis à vis of the bishops, whose secular power was on the wane. The Catholic reaction was strong, in particular at the Abbey of Saint-Maurice, where in 1555 the abbot Jean Miles burned Protestant Bibles that had been confiscated in Conches, ignoring the danger of unleashing a civil war. At the turn of the 17th century, the influence of the Reformation in the Valais was such that not only did many families convert, but two successive bishops and several high bailiffs were very receptive to Protestant ideas. The tide was turned beginning in 1604 with the accession of Adrien II de Riedmatten to the episcopal throne. He adopted the title of "count and prefect of the entire Valais", outlawed Protestant services and threatened to exclude nobles with Protestant inclinations from public office. It was around this time that Capuchin and Jesuit missionaries from the Catholic cantons of Switzerland arrived in the Valais through the Grimsel Pass to join forces with the new bishop and undertake the task of re-catholicising the canton, in particular by establishing convents and Latin schools.
Paul AEBISCHER, "La christianisation du Valais à la lumière de quelques faits linguistiques", in Vallesia, 17 (1962), pp. 171-206.
Gérard DELALOYE, L'évêque, la Réforme et les Valaisans: XVIe et XVIIe siècles, Baden, 2009.