Location in the diocese of Sion, Switzerland where a Roman legion was allegedly martyred
Agaunum (today ST. MAURICE-EN-VALAIS) in the diocese of Sion, Switzerland, owes its fame to an event related by St. Eucherius, Bishop of Lyons, the martyrdom of a Roman legion, known as the "Theban Legion", at the beginning of the fourth century. For centuries this martyrdom was accepted as an historical fact, but since the Reformation it has been the subject of long and violent controversies, an exact account of which may be found in the work of Franz Stolle. The sources for the martyrdom of the Thebans are few, consisting of two editions of their "Acts", certain entries in the calendars and in the martyrologies, and the letter of Bishop Eucherius, written in the year 450. To these may be added certain "Passiones" of Theban martyrs, who escaped from the massacre of Agaunum, but who later fell victims to the persecution in Germany and Italy. It was only in the episcopate of Theodore of Octodurum (369-391), a long time after the occurrence, that attention seems to have been drawn to the massacre of a Roman legion at Agaunum. It was then that, according to St. Eucherius, a basilica was built in honor of the martyrs, whose presence had been made known to Bishop Theodore by means of a revelation. The document of primary importance in connection with this history is the letter of St. Eucherius to Bishop Salvius, wherein he records the successive witnesses through whom the tradition was handed down to his time—over a period, that is, of about one hundred and fifty years. He had journeyed to the place of martyrdom, whither pilgrims came in great numbers, and had, he says, questioned those who were able to tell him the truth concerning the matter. He does not, however, appear to have seen a text of the martyrdom, though his account has many excellent qualities, historical as well as literary. Certain facts are related with exactitude, and the author has refrained from all miraculous additions. But on the other hand, the speeches which he attributes to the martyrs, and the allusion by which he strives to connect the massacre of the Theban Legion with the general persecution under Diocletian have given rise to much discussion. The speeches were probably of the Bishop's own composition; the historical groundwork on which he professes to base the martyrdom is wholly independent of the original narrative. The objections raised against the fact itself, and the attempts made to reduce the massacre of the legion to the mere death of six men, one of whom was a veteran, do not seem to merit attention. Barbarous as it may appear, there is nothing incredible in the massacre of a legion; instances might be cited in support of so unusual an occurrence, though it is quite possible that at Agaunum we have to do not with a legion, but with a simple vexillatio. The silence of contemporary historians, which has been appealed to as an unanswerable argument against the truth of the martyrdom of the Thebans, is far from having the weight that has been given it. Paul Allard has shown this very clearly by proving that there was no reason why Sulpicius Severus, Orosius, Prudentius, Eusebins, or Lactantius should have spoken of the Theban martyrs. He fixes the date of the martyrdom as prior to the year 292, not, as generally received, in 303. Dom Ruinart, Paul Allard, and the editors of the "Analecta Bollandiana" are of opinion that "the martyrdom of the legion, attested, as it is, by ancient and reliable evidence, cannot be called in question by any honest mind". This optimistic view, however, does not seem to have convinced all the critics. (See St. Eucherius of Lyons; St. Maurice).
The letter of Eucherius gives us no details as to the rule imposed on the priests entrusted by Theodore of Octodurum with the care of the basilica at Agaunum; nor do we know whether they were regulars or seculars, though a sermon of St. Avitus, Bishop of Vienne, would appear to indicate the existence of a monastic foundation, which was replaced and renewed by the foundation of Sigismund, King of the Burgundians. Of the two documents which confirm this view, the "Vita Severini Acaunensis" is utterly unreliable, being a tissue of contradictions and falsehoods; the "Vita Sanctorum Abbatum Acaunensium", a work of slight value, to be received with caution, though certain facts may be gathered from it. At the date of Sigismund's first gifts to Agaunum the community was governed by Abbot Enemodus, who died January 3, 516. His next successor but one, Ambrosius, brought Agaunum into notice by an innovation unknown in the West, the Perpetual Psalmody, in 522 or 523 at latest. This Perpetual Psalmody, or laus perennis, was carried on, day and night, by several choirs, or turmae, who succeeded each other in the recitation of the Divine Office, so that prayer went on without cessation. This laus perennis was practiced in the East by the Acoemetae (q.v.), and its inauguration at Agaunum was the occasion of a solemn ceremony, and of a sermon by St. Avitus which has come down to us. The "custom of Agaunum", as it came to be called, spread over Gaul, to Lyons, Chalons, the Abbey of Saint Denis, to Luxeuil, Saint Germain at Paris, Saint Medard at Soissons, to Saint-Riquier, and was taken up by the monks of Remiremont and Laon, though the Abbey of Agaunum had ceased to practice it from the beginning of the ninth century. But Agaunum had gained a worldwide fame by its martyrs and its psalmody. The abbey had some of the richest and best preserved treasures in the West. Among the priceless and artistically exquisite pieces of goldsmith work, we need only mention the chasse (reliquary), decorated with glass mosaic, one of the most important in the West for the study of the beginnings of barbarian and Byzantine art. It ranks with the armor of Childeric, the Book of the Gospels at Monza in Italy, and the crowns of Guarrazar in Spain. It is decorated not only with mosaics, but with tiles and precious stones, smooth or engraved. The front is ornamented with a medallion, long taken for a cameo, but which is a unique piece of work in spun glass. Its date has been much discussed. The back bears a long inscription, which unfortunately affords no solution of the problem, but we may agree with d'Arbois de Jubainville that it is not of earlier date than the year 563.