C. Julius Caesar, Gallic War

Induced by these considerations, and influenced by the authority of Orgetorix, they determined to provide such things as were necessary for their expedition-to buy up as great a number as possible of beasts of burden and wagons-to make their sowings as large as possible, so that on their march plenty of corn might be in store-and to establish peace and friendship with the neighboring states. They reckoned that a term of two years would be sufficient for them to execute their designs; they fix by decree their departure for the third year. Orgetorix is chosen to complete these arrangements. He took upon himself the office of embassador to the states: on this journey he persuades Casticus, the son of Catamantaledes (one of the Sequani, whose father had possessed the sovereignty among the people for many years, and had been styled "friend" by the senate of the Roman people), to seize upon the sovereignty in his own state, which his father had held before him, and he likewise persuades Dumnorix, an Aeduan, the brother of Divitiacus, who at that time possessed the chief authority in the state, and was exceedingly beloved by the people, to attempt the same, and gives him his daughter in marriage. He proves to them that to accomplish their attempts was a thing very easy to be done, because he himself would obtain the government of his own state; that there was no doubt that the Helvetii were the most powerful of the whole of Gaul; he assures them that he will, with his own forces and his own army, acquire the sovereignty for them. Incited by this speech, they give a pledge and oath to one another, and hope that, when they have seized the sovereignty, they will, by means of the three most powerful and valiant nations, be enabled to obtain possession of the whole of Gaul.