The northern region comprising the Po (Padus) plain and its mountain fringes from the Apennines to the Alps was known to the Romans as Cisalpine Gaul. In the middle republic it was not considered part of Italy, which extended only to the foothills of the Apennines along a line roughly from Pisae to Ariminum. Beyond the Apennines lay Gaul, a land inhabited by Celtic peoples whom the Romans looked upon with fear and wonder. (See gaul (transalpine).)
By the early 4th cent. the Gauls had displaced the Etruscans in the Po valley, and had begun to make raids across the Apennines into peninsular Italy (in one of which, c.386 bc, they sacked Rome). Further Gallic invasions occurred sporadically throughout the 4th and 3rd cents., culminating in the great invasion of 225, which the Romans and their Italian allies defeated at Telamon on the Etruscan coast.
The Romans responded by invading Cisalpine Gaul, which they overran in a three‐year campaign of conquest ending with the capture of Mediolanum in 222. Their efforts to consolidate the conquest were interrupted by Hannibal's invasion, which prompted the Gauls to rebel. After defeating Hannibal, the Romans resumed their plan of conquest, which they completed in 191 with a victory over the Boii, the most powerful of the Cisalpine Gallic tribes. Colonies at Placentia and Cremona were refounded, and further colonies were settled at Bononia, 189, Parma, and Mutina. In 187 the via Aemilia was constructed from Ariminum to Placentia. As a result of this great programme of colonization (still evident in aerial photographs which show traces of centuriation throughout the region), nearly all the land south of the Po was occupied by settlers from peninsular Italy, while the northern part of the plain remained largely in the hands of its Celtic inhabitants, who were henceforth known to the Romans as Transpadani.
After the Social War Cisalpine Gaul was formally separated from Italy and became a province, with its southern border at the Rubicon; but all the colonial settlers who were not already Roman citizens were enfranchised. The rest of the free population, which effectively meant the Transpadani, were given Latin rights, a decision that they greatly resented; the demand for full citizen rights became a hot political issue in the following decades, until the Transpadani were finally enfranchised by Caesar in 49. In 42 Cisalpine Gaul was fully integrated within Italy, and under Augustus was divided into four of the eleven administrative regions of Italy (VIII–XI).
In the centuries after 200 Cisalpine Gaul was rapidly and thoroughly Romanized, and few traces of Celtic language and culture remained by the time of the empire. An area of rich agricultural land, much of which was reclaimed by Roman drainage schemes in the lower Po valley, Cisalpine Gaul achieved great prosperity; by the time of Strabo, who gives an eloquent description of it, it had become one of the most prosperous parts of Europe.
Subjects: Classical Studies.