He accomplished his mission with his usual adroitness, and returned to Rome with new honors.

He took an active part in the Social War, eclipsing the fame of his rival, Marius.

He was now the recognized leader of the conservative and aristocratic party.

The feeling between the rivals was more bitter than ever, for Marius, though old, had by no means lost his prestige with the popular party.
It was at this time that Mithradates, learning of the Social War, thought it a good opportunity to advance his own interests and extend his realm.

He collected all his available forces, and invaded Bithynia.
With his fleets he sailed through the Dardanelles into the Archipelago.
The extortions of the Roman governors had been so great, that Ionia, Lydia, and Caria, with all the islands near Asia Minor, gladly revolted from Rome, and accepted his protection.