The franchise law of Drusus secured for him unbounded popularity throughout Italy and bitter opposition at Rome. This opposition in his own city culminated in his assassination in 91 B.C.
The murder of Drusus was the spark which produced the conflagration of the Social War. Losing hope of securing any justice from Rome voluntarily, ten of the Italian tribes, the Samnites, Trentanians, Hirpini, Lucanians, Apulians, Picentines, Vestini, Marrucini, Marsians, and Pæligni banded themselves together and declared war against Rome. The Romans seemed to have been completely taken by surprise. The Roman legates sent to the camp of the Italians were murdered, together with all the Roman citizens upon whom the insurgents could lay their hands, and a policy of extermination was resolved upon. Rome was to be destroyed, and Italy was to be made into a great republic with Corfinium as its capital. The government of the new republic was modeled after that of Rome. Marsian and Mutilus were chosen consuls for the first year of the new Italian republic.
The war at first went against the Romans and for a while it seemed as if the Italians might even succeed in their scheme for the overthrow and the destruction of Rome. Again the Romans were obliged to look to Gaius Marius for their safety. Marius, who shortly before this time had returned from the East and who had been suffered to hold only a subordinate command during the first year of the war, now being put in control of one of the Roman armies turned the tide of the Italian success by winning the first great victory achieved by the Romans during the war. The sympathy of Marius, however, was so strongly with the demands of the Italians, and his desires so great to bring the war to a close by conceding these demands, that he failed to follow up the success with his accustomed vigor, with the result that a younger general was enabled to rise into prominence.
Lucius Cornelius Sulla had already acquired considerable military reputation from the campaign which he had served in Africa under Marius, and was now in command of one of the Roman armies. Sulla, throughout his whole life, was a consistent adherent of the extreme oligarchical party. Nowhere in his life's history do we find the slightest degree of regard for popular rights, or any opposition to injustice which might rest on the lower classes. With no sympathy for the Italians or the cause which they represented, and possessed with military ability almost equal to that of Marius, Sulla became the military hero of the Social War. Nevertheless, it was soon evident that the Romans themselves would not be able to bring the war to a successful termination. Therefore, by the Julian Law, the Roman franchise was extended to those tribes and cities in possession of the Latin rights, who, in return for the grant of the franchise to themselves, seemed to have willingly assisted in preventing its acquisition by the others. With the aid of the Latins, Sulla was able to compel the subjugation of the Italians, of whom more than three hundred thousand are reported to have been killed in the short war.