HELVETII (Ἑλουήτιοι, Ἑλβήττιοι), a Celtic people, whose original home was the country between the Hercynian forest (probably the Rauhe Alp), the Rhine and the Main (Tacitus, Germania, 28). In Caesar’s time they appear to have been driven farther west, since, according to him (Bell. Gall. i. 2. 3) their boundaries were on the W. the Jura, on the S. the Rhone and the Lake of Geneva, on the N. and E. the Rhine as far as Lake Constance. They thus inhabited the western part of modern Switzerland. They were divided into four cantons (pagi), common affairs being managed by the cantonal assemblies. They possessed the elements of a higher civilization (gold coinage, the Greek alphabet), and, according to Caesar, were the bravest people of Gaul. The reports of gold and plunder spread by the Cimbri and Teutones on their way to southern Gaul induced the Helvetii to follow their example. In 107, under Divico, two of their tribes, the Tougeni and Tigurini, crossed the Jura and made their way as far as Aginnum (Agen on the Garonne), where they utterly defeated the Romans under L. Cassius Longinus, and forced them to pass under the yoke (Livy, Epit. 65; according to a different reading, the battle took place near the Lake of Geneva). In 102 the Helvetii joined the Cimbri in the invasion of Italy, but after the defeat of the latter by Marius they returned home. In 58, hard pressed by the Germans and incited by one of their princes, Orgetorix, they resolved to found a hew home west of the Jura. Orgetorix was thrown into prison, being suspected of a design to make himself king, but the Helvetii themselves persisted in their plan. Joined by the Rauraci, Tulingi, Latobrigi and some of the Boii—according to their own reckoning 368,000 in all—they agreed to meet on the 28th of March at Geneva and to advance through the territory of the Allobroges. They were overtaken, however, by Caesar at Bibracte, defeated and forced to submit. Those who survived were sent back home to defend the frontier of the Rhine against German invaders. During the civil wars and for some time after the death of Caesar little is heard of the Helvetii.
Under Augustus Helvetia (not so called till later times, earlier ager Helvetiorum) proper was included under Gallia Belgica. Two Roman colonies had previously been founded at Noviodunum (Colonia Julia Equestris, mod. Nyon) and at Colonia Rauracorum (afterwards Augusta Rauracorum, Augst near Basel) to keep watch over the inhabitants, who were treated with generosity by their conquerors. Under the name of foederati they retained their original constitution and division into four cantons. They were under an obligation to furnish a contingent to the Roman army for foreign service, but were allowed to maintain garrisons of their own, and their magistrates had the right to call out a militia. Their religion was not interfered with; they managed their own local affairs and kept their own language, although Latin was used officially. Their chief towns were Aventicum (Avenches) and Vindonissa (Windisch). Under Tiberius the Helvetii were separated from Gallia Belgica and made part of Germania Superior. After the death of Galba (A.D. 69), having refused submission to Vitellius, their land was devastated by Alienus Caecina, and only the eloquent appeal of one of their leaders named Claudius Cossus saved them from annihilation. Under Vespasian they attained the height of their prosperity. He greatly increased the importance of Aventicum, where his father had carried on business. Its inhabitants, with those of other towns, probably obtained the ius Latinum, had a senate, a council of decuriones, a prefect of public works and flamens of Augustus. After the extension of the eastern frontier, the troops were withdrawn from the garrisons and fortresses, and Helvetia, free from warlike disturbances, gradually became completely romanized. Aventicum had an amphitheatre, a public gymnasium and an academy with Roman professors. Roads were made wherever possible, and commerce rapidly developed. The old Celtic religion was also supplanted by the Roman. The west of the country, however, was more susceptible to Roman influence, and hence preserved its independence against barbarian invaders longer than its eastern portion. During the reign of Gallienus (260–268) the Alamanni overran the country; and although Probus, Constantius Chlorus, Julian, Valentinian I. and Gratian to some extent checked the inroads of the barbarians, it never regained its former prosperity. In the subdivision of Gaul in the 4th century, Helvetia, with the territory of the Sequani and Rauraci, formed the Provincia Maxima Sequanorum, the chief town of which was Vesontio (Besançon). Under Honorius (395–423) it was probably definitely occupied by the Alamanni, except in the west, where the small portion remaining to the Romans was ceded in 436 by Aëtius to the Burgundians.
See L. von Haller, Helvetien unter den Römern (Bern, 1811); T. Mommsen, Die Schweiz in römischer Zeit (Zürich, 1854); J. Brosi, Die Kelten und Althelvetier (Solothurn, 1851); L. Hug and R. Stead, “Switzerland” in Story of the Nations, xxvi.; C. Dändliker, Geschichte der Schweiz (1892–1895), and English translation (of a shorter history by the same) by E. Salisbury (1899); Die Schweiz unter den Römern (anonymous) published by the Historischer Verein of St Gall (Scheitlin and Zollikofer, St Gall, 1862); and G. Wyss, “Über das römische Helvetien” in Archiv für schweizerische Geschichte, vii. (1851). For Caesar’s campaign against the Helvetii, see T. R. Holmes, Caesar’s Conquest of Gaul (1899) and Mommsen, Hist. of Rome (Eng. trans.), bk. v. ch. 7; ancient authorities in A. Holder, Altkeltischer Sprachschatz (1896), s.v. Elvetii.