The battle of Vercellae or the Raudian Plain (30 July 101 BC) was the final battle of the Cimbric War and saw Marius destroy the Cimbri at an uncertain location in northern Italy.
In 102 BC the Cimbri reappeared in Gaul after a failed invasion of Spain. In previous years they had decided not to invade Italy, but it perhaps now appeared to be their last option, having failed in Gaul and Spain. They found new allies - the Teutones, Ambrones, Tigurini and the Toygeni, and came up with a plan for a two-pronged invasion of Italy. The Teutones and Ambrones were to attack from the north-west, the Cimbri and other allies from the north-east.
The two forces probably split up in 102 BC, before the first clash of the campaign. The Roman consuls for the year were each given one front to defend. Marius joined the army already in Gaul, where he inflicted a crushing defeat on the Teutones and Ambrones at Aquae Sextiae, eliminating that threat. Soon afterwards he discovered that he had been elected as one of the consuls for 101 BC, his fifth year in office and fourth consecutive year.
His colleague for 102 C, Q. Lutatius Catulus, was given the task of defending the Alps against the Cimbri and their allies. In the event only the Cimbri actually took part in the campaign, but he was still unable to cope. His first plan was to defend the Alpine passes, but at some point he withdrew into Italy, and attempted to defend the line of the Atiso (the modern Adige). Catulus wrote a lost account of this campaign, which appears to have distorted some of the surviving accounts of the campaign. Plutarch describes his failure to hold the Alps as a deliberate move, to avoid having to split his forces into many parts, but Frontinus and Livy both suggest that Catulus suffered a defeat in the mountains and was forced to retreat.
His attempt to hold the Adige also failed. He built a bridge across the river, and camped on the west bank, but the Cimbri camped upstream, built a dam to divert the river and sent heavy objects floating down the river to smash into the bridge. Catulus lost control of his army, which began to retreat away from the river, leaving one cohort isolated in a mountain castle. Plutarch, clearly influenced by Catulus's own writings, describes the consul as bravely leading the retreat, so that the shame of the defeat would fall on him and not on his army, a rather unconvincing argument! The isolated cohert either fought their way to safety, or was allowed to go by the Cimbri, depending on which source you believe. Catulus wasn't able to convince his men to stop until they had crossed the Po. Large parts of north-eastern Italy had thus fallen to the Cimbri.
After successfully crossing the Alps, the Cimbri stopped in the Venetia, possibly hoping to be able to settle in the area (or waiting for the expected arrival of the Teutones and Ambrones). Whatever their reason was, this gave Marius time to visit Rome, turn down a triumph until the war was completed, and then summon his army from Gaul. Once his troops had arrived he joined up with Catulus, and advanced across the Po. A period of negoations followed, with the Cimbri asking for land to settle on, and claiming that they were waiting for the Teutones to arrive. Marius eventually had to produce the captured Teutone kings to prove that they had been defeated. According to Plutarch Boeorix, king of the Cimbri, then challenged Marius to set the day and place for the battle. Marius agreed to this, picking the plain of Vercellae, and a date three days hence (30 July 101 BC). Other sources (including Velleius and Florus) place it on the Raudian Plain. Neither of these locations can be accurately pinned down.
For once we have some idea of the size of the Roman army at this battle. Plutarch, using Sulla's autobiography as his source, gives Marius 32,000 men and Catulus 23,300. Marius posted Catulus in the centre of the line, and split his army in two, placing part on each wing. Sulla and Catulus both claimed that Marius had done this in the hope that his troops would gain all of the credit for any victory, as the centre would end up folded out of the line. Given that Catulus's men had suffered two defeats and lost control of north-eastern Italy, while Marius's men had defeated the Teutones, this would be an entirely sensible plan.
Plutarch gives the Cimbri a total of 180,000 people, including women and children, with 15,000 cavalry. Orosius gives them 200,000 men. The Cimbri advanced in a massive infantry square, with the cavalry advancing in a line ahead of the infantry.
We have several accounts of the battle, most of which include several of the same features - including a misty start to the day, a Cimbric cavalry attack, dust clouds and the glare of the sun causing problems for the Cimbri - but give them a different emphasis.
Plutarch gives us a length account of the battle, but one that isn’t entirely convincing, and is clearly distorted by his use of Sulla and Catulus as sources. The battle began with the Cimbric cavalry advancing, but then swerving to the right to try and draw the Roman infanty into the gap between the Cimbric cavalry and infantry. Marius saw through this ploy, but was unable to stop the infantry from attempting to catch the cavalry. The Cimbri infanty then began to attack, while Marius and Catulus paused to make sacrifices that predicted victory.
Marius then led his troops into the attack, but so much dust had been thrown up that they were unable to find the Cimbric infantry and spent some time moving across the plains without getting engaged in the battle. As a result the bulk of the fighting fell onto Catulus's men. The Romans were now helped by the sun, which was shining onto the faces of the Cimbri, blinding them, and causing them to overheat. This part of his account doesn't really make sense - the Romans were massively outnumbered by the Cimbri, and it really would have been rather difficult for Marius's men to get so lost in dust that they could find an enemy that was right in front of them! If the dust had been that thick, then the sun wouldn't have been a factor. Finally, the Cimbri hadn’t just come from the north, but had spent about a decade campaigning in southern Gaul and Spain, so would have been used to the heat.
Plutarch gives few details of the rest of the battle. The best of the Cimbri were killed where they were fighting, as the front lines were chained together to prevent their lines from being broken. After their defeat the survivors fled back towards the camp, where many of them were killed by the Cimbric women, who then killed themselves and their children. Marius's men appear to have captured the camp, taking the loot, while Catulus's men captured the battle standards and trumpets. This perhaps suggests that Marius's plan was more sophisticated than Plutarch gives him credit for, with his men on the flanks going around the Cimbric infantry block and either attacking their rear or camp, while Catulus kept the main part of the army engaged (similar to Hannibal's plan at Cannae). The Romans took 60,000 prisoners, while 120,000 men were said to have been killed.
Orosius says that Marius picked the battlefield so that he could deploy his men under the cover of morning mist. The Cimbri were caught out by this and thrown into confusion. The sun blinded them and dust was blown into their eyes. The initial cavalry assault was defeated, and the retreating cavalry disrupted the loose infantry formation. They lost 140,000 men in the battle, and another 60,000 as prisoners, close to Plutarch's figures. Orosius has the women defend the camp before eventually giving up and committing suicide. He gives figures of 340,000 dead and 140,000 prisoners, but includes the losses at Aquae Sextiae in this total.
Florus gives the Cimbric losses at 65,000 men, the Romans as only 300 and has the battle lasting all day. He also mentions the mist, having Marius use it to cover a surprise Roman attack, the dust and the sun. He turned the massacre at the Cimbric camp into a second battle against the armed women, who defended the camp with pikes and axes before being defeated.
Although we can never be entirely sure exactly what happened, these various accounts suggest that the battle started with a surprise Roman attack covered by the mist. The Cimbri responded with a cavalry attack, which was repulsed. The retreating cavalry disrupted their infantry formation, allowing the Romans to win a total victory. Marius's army, on the flanks, may have got into the enemy rear, adding to the chaos.
In the aftermath of this victory, Marius was hailed as the third founder of Rome, for having completely defeated a barbarian threat that had been looming over the city for more than a decade. He showed good judgement on his return to Rome, only agreed to celebrate a triumph if it could be shared with Catulus. He then went on to be elected consul for a sixth time, but this time he got drawn into the politics of the city, and was less successful than in battle. Despite his later failings, Marius played a major role in saving the Republic from a serious threat.