The battle of Lake Vadimon (283 BC) was a Roman victory over a Gallic and Etruscan army fought only forty miles to the north of Rome and that marked the start of Rome’s rivalry with the Boii while also coming towards the end of their wars with the Etruscans (Gallic War of 284-283 BC).
Our only account of the battle comes from Polybius. The fragments of Appian also mention the same war, but don’t directly mention this particular battle.
According to Polybius the war started when the Gauls besieged Arretium (Arezzo in modern Tuscany). The Romans sent an army under the Praetor Lucius Caecilius to lift the siege, but this army was defeated and the Praetor was killed. His successor, Manius Curius, sent legates to negotiate the return of some Roman prisoners, but they were murdered. This triggered a Roman invasion of the Senones homeland on the Adriatic coast in which the Gauls were defeated in battle and their homeland devastated. The Romans then planted a colony at Sena, near modern Ancona, the first time that they had expanded into areas previous held by the Gauls.
This Roman success worried the Boii, the Gallic tribe that lived north of the Senones up the Adriatic coast. They formed an alliance with the remaining Etruscans, who still held some areas to the north of Rome. The two armies united, but were then defeated by a Roman army led by an unnamed commander at Lake Vadimon. This almost dry lake is only forty miles to the north of Rome, just to the west of the Etruscan town of Hurta (modern Orte). According to Polybius most of the Etruscans were killed and not many of the Boii escaped.
In the following year the Etruscans and Boii managed raise a second army, this time including those too young to normally fight. However this army was defeated in a second, unnamed battle, and in the aftermath of this defeat the Etruscans and Boii sued for peace.
It is possible that the consul P.Cornelius Dolabella was the Roman commander at this battle, although this interpretation depends on a combination of the contradictory accounts in Polybius and Appian and makes two assumptions. In Polybius’s account, the war started with a Gallic siege of Arretium and the defeat of a Roman army under the Praetor Lucius Caecilius. Roman envoys were then murdered, and an unnamed Roman general invaded the Gallic lands, defeated an army of Senones at an unnamed battle and ravaged the area. The Boii then combined with the Etruscans, and this force was defeated at Lake Vadimon. In Appian we start with the ambassadors being sent to complain that the Gauls were breaking an existing treaty by providing aid to the Etruscans, and being murdered by a Gallic leader named Britomaris because his father had been killed earlier in the same war. The Consul P. Cornelius Dolabella invaded the Senones homeland in revenge. Two assumptions have to be made in order to make Dolabella the commander at Lake Vadimon. The first is that this was indeed the otherwise unnamed fight in which Britomaris’s father was killed. The second is Dolabella’s army was available to invade the Senones homeland because it had previously fought at Lake Vadimon. However we have no evidence to support either of those assumptions.
However Appian’s account does give us a probable date for the battle, as the two consuls in his account were in office in 283 BC. A Lucius Caecilius had been consul in 284 BC, so if he was the same man defeated at Arretium then that battle would also need to have been fought in 283, after his time as consul was over.
The fighting at Lake Vadimon was one of the last battles between the Romans and the Etruscans, and came only twenty years before the final defeat of the last independent Etruscan cities. However it also marked the start of a long rivalry with the Boii that lated until their defeat at Mutina in 193 BC.