The location of the final battle between the Aedui and their enemies, which Caesar names as the Battle of Magetobriga, remains unknown, but Ariovistus’ fifteen thousand men turn the tide, and the Aedui become tributary to the Sequani.

Cicero will write in 60 BCE of a defeat sustained by the Aedui, perhaps in reference to this battle.

Ariovistus seizes a third of the Aeduan territory, settling one hundred and twenty thousand Germans there.

In order to avoid infringing on his allies for the moment, Ariovistus must have passed over the low divide between the Rhine and the Doubs in the vicinity of Belfort and then have approached the Aedui along the Ognon river valley.

That move leaves the Sequani between him and the Jura mountains, not a tolerable situation for either if they are not going to be allies.

Ariovistus makes the decision to clear out the Sequani from the strategic Doubs valley and repopulate it with Germanic settlers.

He demands a further third of Celtic land for his allies the Harudes.

Caesar makes it clear that Germanic tribes are actually in the land of the Sequani and are terrorizing them.

They are said to have controlled all the oppida, but this statement is not entirely true, as Vesontio is not under Germanic control.

Presumably, the country to the north of there is under Germanic control.

By the end of the campaign, the non-client Suebi, under the leadership of Ariovistus, stand triumphant over both the Aedui and their co-conspirators.

Rome, fearing another mass migration akin to the devastating Cimbrian War, and now keenly invested in the defense of Gaul, will be drawn irrevocably into war.

Ariovistus, chieftain of the Germanic Suebi tribe, had resumed the tribe’s migration from eastern Germany to the Marne and Rhine region in 71 BCE.

Despite the fact that this migration encroaches on Sequani land, the Gaulish Sequani seek Ariovistus’ allegiance against the Aedui, a numerous Celtic people occupying the drainage system of the upper Loire.

They are nearly between their neighbors to the northeast, the Sequani, who occupy the Doubs river valley, and the Arverni in the Massif Central.

When, in about 62 BCE, a Gaulish Roman client state, the Arverni, conspires with the Sequani and the Germanic Suebi nation east of the Rhine to attack the Aedui, a strong Roman ally, Rome turns a blind eye.

The Romans appear to be unconcerned about a conflict between non-client, client and allied states.

the Suebic leader Ariovistus and the events he was part of are known from Caesar's Commentarii de Bello Gallico.

Caesar, as a participant in the events, is a primary source, although as his Commentaries are in part political propaganda they may be suspected of being self-serving.

Later historians, notably Dio Cassius, are suspicious of his motives.

Caesar does not say what the cause of the conflict was, but the Sequani control access to the Rhine river along the valley of the Doubs.

To that end, they have gradually built up an oppidum or fortified town at Vesontio.

Tradesmen headed up the Rhone and its tributary the Saône (the ancient Arar) cannot pass the Doubs at Vesontio without coming to terms with the Sequani, nor can anyone pass from the Rhine to the Rhone except on similar terms.

The east of the entire great channel is bordered by the Jura mountains and the west by the Massif Central.

Vesontio is seventy-five miles (one hundred and twenty-one kilometers) from that stretch of the Rhine between Mulhouse and Basel.

The Arar forms part of the border between the Aedui and the Sequani.

Strabo, who lived a generation after Caesar in the late republic and early empire, does make a statement concerning the cause of the conflict between the Sequani and Aedui, and it was in fact commercial, at least in Strabo's view.

Each tribe claimed the Arar and the transportation tolls from traffic along it, "but now", says Strabo, "everything is to the Romans."

The Sequani also habitually supported the Germans in their previous frequent expeditions across the river, which shows that Ariovistus’ subsequent devastation of Sequani lands represented a new policy.

The Sequani reward Ariovistus with land in 61 BCE following his victory in the Battle of Magetobriga.

Ariovistus settles the land with one hundred and twenty thousand of his people.

When twenty-four thousand Harudes join his cause, Ariovistus demand that the Sequani give him more land to accommodate the Harudes people.

This demand 'concerns' Rome because if the Sequani concede, Ariovistus will be in a position to take all of the Sequani land and attack the rest of Gaul.

By this time, the Helvetii are well on their way in the planning and provisioning for a mass migration under the leadership of the wealthy aristocrat Orgetorix, who has persuaded the Helvetians to attempt to migrate from Helvetian territory to southwestern Gaul (modern-day France).

The reasons for their migration are mentioned by Caesar in separate passages as either harassment by the Germanic tribes, or not being able to in turn raid for plunder themselves due to their situation in hilly and mountainous territory.

Via council and parley, Orgetorix makes clandestine negotiations with the ambitious Sequani and the Roman-dominated Aedui.

The Sequani are beginning to resent and regret the abundance of unruly Germanic war bands and their huge encampments of dependents.

The Aedui are loath to obey the Roman spur any longer than they must and are keen to revisit their former days at council.

The parley for the trek is successful and Orgetorix is granted passage, and with the trek ratified by council, an army is called up and provisioned.

During this process, Orgetorix had also succeeded in making a personal alliance with the Sequanii chieftain Casticus and the Aedui chieftain Dumnorix through marital arrangements and host exchange of family members.

Orgetorix's Gallic rivals allege that these political successes and displays of diplomacy are intended to benefit Orgetorix alone and their claims are made more convincing by Roman intrigues and impositions.

The majority of the Gallic tribes congratulate Caesar following his victory over the Helvetii, and seek to meet with him in a general assembly.

Diviciacus, the head of the Aeduan government and spokesmen for the Gallic delegation, expresses concern over Ariovistus’ conquests and the hostages he has taken.

Diviciacus demands that Caesar defeat Ariovistus and remove the threat of a Germanic invasion otherwise they would have to seek refuge in a new land.

Not only does Caesar have a responsibility to protect the long-standing allegiance of the Aedui, but this proposition presents an opportunity to expand Rome’s borders, strengthen the loyalty within Caesar’s army and establish him as the commander of Rome’s troops abroad.

As the Senate had declared Ariovistus a “king and friend of the Roman people” in 59 BCE, Caesar cannot declare war on the Suebi tribe.

Caesar, saying that he cannot ignore the pain the Aedui have suffered, delivers an ultimatum to Ariovistus demanding that no German cross the Rhine, the return of Aedui hostages and the protection of the Aedui and other friends of Rome.

Although Ariovistus assures Caesar that the Aedui hostages will be safe as long as they continue their yearly tribute, he takes the position that he and the Romans are both conquerors and that Rome has no jurisdiction over his actions.

With the attack of the Harudes on the Aedui and the report that a hundred clans of Suebi are trying to cross the Rhine into Gaul, Caesar has the justification he needs to wage war against Ariovistus in 58 BCE.

Learning that Ariovistus intends to seize Vesontio, the largest town of the Sequani, Caesar commences marching his troops toward Vesontio.

Some of Caesar’s officers hold their posts for political reasons only and have no war experience.

As a result, they suffer from poor morale which threatens Caesar’s campaign.

Caesar challenges the officers and their legions, saying that the only legion he can trust is the Tenth.

With their pride on the line, the other legions follow the Tenth’s lead, determined not to be outdone.

Consequently, Caesar arrives in Vesontio before Ariovistus.

They meet and rout the Germanic army in the land between the city and river, effecting a massacre as the Germans try to escape over the river.

Most of Ariovistus’ hundred and twenty thousand men are killed.

Some, including Ariovistus himself, manage to cross the river in boats or by swimming.

The rest are cut down by Roman cavalry, including both of Ariovistus's wives and one of his daughters; another daughter is taken prisoner.

Ariovistus and what remains of his troops escape and cross the Rhine, never to engage Rome in battle again.

Both Caesar's emissaries are rescued unharmed, to relate their harrowing adventures as the Germans debated (in their presence) whether they should be burned then or later.

Caesar said that encountering Procillus and freeing him from his chains gave him as much pleasure as the victory, which offers some insight into the emotional climate of Caesar's forces; the officers were a sort of family.

The fate of the twenty-four thousand Harudes is not known.

The Suebi encamped near the Rhine return home.

Caesar is victorious.

The Sequani in 71 BCE, before the arrival of Julius Caesar in Gaul, had taken the side of the Arverni against their rivals the Aedui and hired the Suebi under Ariovistus to cross the Rhine and help them.

Although his assistance had enabled them to defeat the Aedui, the Sequani were worse off than before, for Ariovistus had deprived them of a third of their territory and threatened to take another third, while subjugating them into semi-slavery.

The Sequani had then appealed to Caesar, who had driven back the Germanic tribesmen in 58 BCE but at the same time obliged the Sequani to surrender all that they had gained from the Aedui.

This had so exasperated the Sequani that they have joined in the revolt of Vercingetorix and share in the defeat at Alesia in 52.

Caesar takes the region of Franche-Comte in eastern Gaul, occupied by the Sequani since the fourth century.

Verginius' forces easily defeat those of Vindex at the Battle of Vesontio in May 68, and the latter commits suicide.

However, after putting down this one rebel, Verginius' legions attempt to proclaim their own commander as emperor.

Verginius refuses to act against Nero, but the discontent of the legions of Germany and the continued opposition of Galba in Spain does not bode well for Nero.

The district known as Sequania had formed part of Belgica under Augustus..

After the death of Vitellius, the inhabitants refuse to join the Gallic revolt against Rome instigated by Gaius Julius Civilis and Julius Sabinus, and drive back Sabinus, who has invaded their territory.

A triumphal arch at Vesontio (Besançon), which in return for this service is made a colony, possibly commemorates this victory.

Diocletian adds Helvetia, and part of Germania Superior to Sequania, which is now called Provincia Maxima Sequanorum, Vesontio receiving the title of Metropolis civitas Vesontiensium.