The history of the Canton of Jura spans from prehistoric times through the formation of the Prince-Bishopric of Basel, its incorporation into the Canton of Bern in 1815, and ultimately the creation of the Canton of Jura as Switzerland's newest canton in 1979.
Prehistory and antiquity
Paleolithic and Mesolithic periods Rich flint-working workshops have been attested from the Riss-Würm interglacial (Eemian) at Alle, at the site called Noir Bois, dating to approximately 120,000 years ago. The Mousterian culture, associated with Neanderthal populations, continued there periodically until around 35,000 BC. The flint deposits of Alle (Noir Bois and Pré Monsieur) and Löwenbourg provided raw materials exploited on site, mainly during warming periods that punctuated the last ice age (Würm, 35,000 to 8000 BC). The tens of thousands of flakes collected show an industry characterized by Levallois-type production. The main objects are scrapers, notches, and denticulates. These sites have also yielded tools carved from flints and quartzites from the northern foot of the Jura chain, the southern or eastern flanks of the Vosges and the Black Forest. Some pieces originate from the Swiss Plateau, from the regions of Olten and Orvin. Animal bones (mammoths, woolly rhinoceroses, hyenas, horses, reindeer) have been found on the Bure plateau as well as at Alle, Boncourt, Bure, Courtedoux, Courtemaîche, and Porrentruy. Most of the Jurassian caves sheltered cave bears. In the caves of Saint-Brais, Frédéric-Edouard Koby discovered a Neanderthal human incisor and some carved flints.
Around 13,000 BC, as the climate warmed, some Magdalenian individuals stopped at Alle - Noir Bois where they carved flint bladelets to repair their spears, using local siliceous material or working Bendorf flint (Haut-Rhin) they had brought with them. The transition to the Mesolithic, called Azilian, was uncovered at Löwenbourg. A laminar industry using local flint, dated from 12,000 to 10,000 BC, includes backed points and blades, truncated blades, burins, scrapers, and borers.
With climate warming, the return of forests, and the appearance of new characteristic fauna (deer, roe deer, wild boar, aurochs, beaver, wolf), human groups adapted to a different environment. According to discoveries, they remained confined to Ajoie and the Laufental, downstream of Liesberg. The valleys of Delémont and the Bernese Jura have yielded nothing from this period. Located in a lateral valley of the Doubs valley on the territory of the former commune of Saint-Ursanne, the small rock shelter of Les Gripons revealed a microlithic industry rich in triangular armatures, dated around 8000-7000 BC. The flint worked on site is essentially of local origin, showing these populations' adaptation to a limited region. Leather working is also attested at the same site, which was occupied temporarily. Two millennia later, another human group from the recent Mesolithic, carrying a microlithic industry (trapezoids and blades with notches and irregular retouches, Montbani type), frequented this shelter, probably to make bows. Other Mesolithic traces have been uncovered at Porrentruy and around Bure.
Neolithic period The beginnings of sedentarization and neolithization (livestock farming and agriculture) remain very discreet in Ajoie. The region nevertheless lies at the confines of the two major currents specific to Western Europe: the Danubian, occupying the plains of Central Europe, and the Mediterranean, ascending the Rhône and Saône valleys. Some Franco-Comtois caves close to the Jura yielded ceramics characteristic of the second half of the 5th millennium. At the same period, long-distance exchanges developed. Polished stone axes of Vosges origin passed through the Jura toward the lakes of the Swiss Plateau (Zurich, Bienne, Neuchâtel). Two examples were discovered at Alle, whose flint, like that of Löwenbourg, is found in lakeside sites dating from 4000 to 2000 BC.
The Jura chain was therefore regularly crossed. However, pollen and sediment analyses seem to indicate that no site in the Delémont valley was yet inhabited. In Ajoie, a habitat is attested at Alle - Sur Noir Bois, probably from the end of the Middle Neolithic, around 3500 BC. Moreover, the Pierre Percée of Courgenay, the frontal slab of a dolmen, is the last vestige of a collective burial monument erected around 3000 BC according to customs specific to the northern flank of the Jura chain. It proves the presence of one or more villages nearby. The only one found to date (Alle - Noir Bois) dates from 2300 BC, from the end of the Neolithic, that is, the Bell Beaker period. Poorly preserved, nothing is known of its extent or architecture. Livestock farming (cattle, pigs, goats, sheep) and agriculture were practiced there. Exchanges with populations from Alsace and southern Germany are evident. More eastern influences, as well as with the Rhône valley, are perceptible. The priority exploitation of local resources (flint, clays) proves thorough knowledge of the region and long-standing settlement. Other contemporary sites are recognized in several places in Ajoie.
Bronze and Iron Ages The beginning of the Bronze Age seems to coincide with demographic evolution. An increase in signs of human presence is observed throughout the 2nd millennium. The Ajoie plain and the Delémont valley were progressively colonized. Numerous small habitats and isolated farms dotted the foot and flanks of hillsides at the end of the Middle Bronze Age and the beginning of the Late Bronze Age. At the threshold of the Franches-Montagnes plateau, the caves of Saint-Brais yielded fairly significant ceramic material from the end of the Middle Bronze Age. Opposite, near Lajoux, pollen analyses showed that clearings took place from this period, suggesting cattle summering. A contemporary site is reported at the summit of Mont-Terri in Ajoie. That of Le Roc, in the commune of Courroux, is an important Late Bronze Age deposit. Perched in the rocks overlooking the passage of the Vorbourg gorge, it dominates the eastern access passage to the Delémont valley.
Social life developed and became hierarchical. The two necropolises of Alle - Les Aiges and Delémont - En La Pran testify to the cremation rite. The oldest burials (Les Aiges) date back to the beginning of the Late Bronze Age. The Delémont necropolis suggests a separation of the burial area. It yielded glass paste beads, proof of relations with Mediterranean milieus. The gold threads found at Alle testify to connections with the Meuse and Marne regions.
The few objects or sites from the early Iron Age (800-480 BC) can also be related to funerary rites, but, as on the Swiss Plateau, this period corresponds to a rarefaction of archaeological data. No habitat is currently known with certainty. The second Iron Age (480-15 BC) is better known, thanks to farms with granaries dated to the early La Tène culture (Alle - Noir Bois), a midden (Courtételle - Tivila), a habitat (Courrendlin - En Solé), and five sites from the late La Tène at Alle (Pré au Prince and Pré Monsieur), Chevenez (Combe Varu and forge of la Combe en Vaillard), and Mont-Terri (oppidum).
Roman period According to writings by Roman authors, particularly Julius Caesar in his De Bello Gallico, the Gallic tribe of the Sequani then occupied the Jura region. At war against the Aedui, they called on Germanic reinforcements from Ariovistus, who were defeated by Caesar at the battle of Ochsenfeld in Alsace (58 BC). The summit of Mont-Terri may have been fortified with a murus Gallicus in these circumstances, related both to the exodus of the Rauraci and Helvetii and to the invasion of Germanic peoples.
The construction of villae and roads at the beginning of the 1st century AD marks the passage of the Jura mountains into Rome's orbit, with most establishments built on Gallic sites. Following the layout of Celtic beaten-earth paths, the Romans consolidated them with stones and gravel in the 30s AD. The current cantonal territory is located at an intersection of the Roman road that then crossed the Jura. From the Swiss Plateau, the road passed through the Pierre-Pertuis pass and Bellelay. At the western end of the Delémont valley, a branch departed toward Augusta Raurica (Augst) following the Birs. Continuing through the La Caquerelle-Les Rangiers pass, the main road crossed Ajoie toward Epomanduodurum (Mandeure), where it met the great artery along the northern flank of the Jura chain, linking Augusta Raurica to Vesuntio (Besançon). The strategic importance of this route disappeared once the Empire's border on the Rhine was pushed further east, after Vespasian's conquest of the Agri Decumates in 73-74 AD.
The vestiges of Gallo-Roman villae scattered throughout Ajoie and the Delémont valley are distributed across the entire territory, except the Bure plateau where water is lacking. The only sign of a presence in the Franches-Montagnes corresponds to the probable relay at Lajoux, on the Pierre-Pertuis road. Some sites preserve signs of certain wealth (Buix, Develier, Vicques) with decorated floors, painted walls, and imported tableware. Others appear more modest (Boécourt, Damvant). A mausoleum was erected in the Delémont plain, attached like the entire valley to Germania Superior, then probably included in the civitas Rauracorum with Upper Alsace following Domitian's territorial reorganization (86 AD). Ajoie, where a Gallo-Roman sanctuary (fanum) was built north of Porrentruy, remained Sequanian, with Mandeure and the Doubs. Both joined the Provincia Maxima Sequanorum created by Diocletian (284–305) by uniting Helvetii, Rauraci, and Sequani.
In 260–261, Alemanni raiding expeditions caused significant destruction. Some villae were abandoned, others partially repaired for a few decades. Mont-Terri was again fortified and probably occupied for some time at the beginning of the 4th century by Roman armies. In the middle of the same century, the Alemanni took advantage of struggles between the official emperor Constans and the usurper Magnentius to definitively erase the Roman presence in the Jurassian countryside, in 353-354 and then in 378. Monetary deposits found in the region highlight these two major destructive waves. Some Roman coins from the end of the 4th century suggest the maintenance of certain activity, but neither archaeology nor history reveals the slightest sign of life in the territory of Canton Jura in the 5th century. Only a few villages preserve a toponym of Latin origin. Like Chevenez, Montignez, or Vicques, they testify to continuity of habitation.
Early Middle Ages In contrast, from the 6th century onward, fairly dense soil occupation is observed, both in Ajoie and in the Delémont valley, where the rural habitat of Develier - Courtételle proves that iron ore reduction was in full swing. This activity encouraged smelters to settle further south, notably around Corcelles and Court, as indicated by the low furnaces and heaps of slag found there. From the second half of the 6th century and especially in the 7th century, numerous necropolises confirm this marked human presence. The importance and wealth of the Merovingian cemetery of Bassecourt, discovered and excavated in the mid-1870s, suggest the existence of a Frankish aristocracy in this main town of the Sornegau, a province extending to the sources of the Birs, probably under the domination of the dukes of Alsace within Austrasia. The Alsegau, a vast territory that encompassed present-day Ajoie, remained attached to the diocese of Besançon and the kingdom of Burgundy. The 7th century demographic development, the wealth of iron ore, and the connecting route to the Swiss Plateau attracted evangelizing monks, notably the future saints Ursanne (who settled in the Clos du Doubs) and Germain (first abbot of Moutier-Grandval).