Roman–Gallic wars

• 1. The Sack of Rome

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  In the year 390 BC, a Gallic army led by Brennus marched on the city of Rome. The Senones tribe had entered Italy from the north and plundered territory in Etruria and Latium. Roman forces attempted to stop them at the Battle of the Allia but were defeated. Brennus then led his men into Rome without further opposition. They plundered the city and departed laden with booty. Some traditions claim the Gauls were later defeated by a Caeretan army or by Camillus. This event marked the first major conflict between Romans and Gauls who settled south of the Alps.

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• 2. Conquest of Cisalpine Gaul

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  Following the Punic Wars, Rome found itself in near-total control of Italy including Cisalpine Gaul. A concerted policy aimed at conquering Gallic territories south of the Alps emerged during the second century BC. Rome invaded the territory of the Insubres in 223 BC and took Clastidium, Acerrae and Mediolanum in 222 BC. During the Second Punic War from 218 to 201 BC, many Gauls sided with Carthage against Rome. After the war ended, Rome took Bononia in 196 BC, Placentia in 194 BC, and Mutina in 193 BC. Many surviving Boii retreated north across the Alps to what became known as Boihaemum.

• 3. Crossing the Alps

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  Between 125 and 121 BC, Roman armies crossed the Alps to fight tribes like the Salluvii and Vocontii. They then engaged the Allobroges and Arveni in battle. The Gauls were decisively defeated at the Battle of Vindalium and the Battle of the Isère River in 121 BC. This victory allowed Rome to annex the Allobrogian territory into a new province called Gallia Transalpina. Later this region became known as Gallia Narbonensis. The crossing marked a shift from defending Italian borders to expanding beyond them.

• 4. The Cimbrian Crisis

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  During the Cimbrian War, Germanic and Gallic allies inflicted devastating defeats on Roman armies. In 109 BC, the Cimbri defeated consul Marcus Junius Silanus. By 107 BC, the Cimbri and Ambrones together with their Helvetii allies defeated a Roman army near Agendicum. Consul Lucius Cassius Longinus was killed during the Battle of Burdigala. These losses exposed vulnerabilities in Roman military power against northern invaders. The crisis forced Rome to reorganize its legions and rethink strategies for dealing with mobile tribal forces.

• 5. Caesars Systematic Campaigns

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  From 58 to 50 BC, Julius Caesar led a series of campaigns through Gaul that he chronicled in detail. His actions resulted in the near-complete subjugation of the country between the Atlantic Ocean and the Rhine River. After discovering that some Gauls were receiving aid from Britain, Caesar mounted the first Roman military expedition to that island. He wrote Commentarii de Bello Gallico to document these events. Plutarch later recorded details about Caesar's life and his Gallic Wars in biographical accounts. This period brought most of western Europe under direct Roman control.

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• 6. Final Suppression of Revolts

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  Between 40 and 37 BC, Marcus Vipsanius Agrippa marched against the Aquitani following unrest in Gaul. He successfully defeated them and secured Roman authority over the region. Later, from 28 to 27 BC, Marcus Valerius Messalla Corvinus suppressed another revolt in Aquitania. For this achievement, Messalla Corvinus celebrated a triumph in Rome. These final operations ensured lasting Roman control over western Europe after decades of conflict. The consolidation marked the end of major resistance from Celtic tribes in the region.