Gallic War

There was left one way, [namely] through the Sequani, by which, on account of its narrowness, they could not pass without the consent of the Sequani. As they could not of themselves prevail on them, they send embassadors to Dumnorix the Aeduan, that through his intercession, they might obtain their request from the Sequani. Dumnorix, by his popularity and liberality, had great influence among the Sequani, and was friendly to the Helvetii, because out of that state he had married the daughter of Orgetorix; and, incited by lust of sovereignty, was anxious for a revolution, and wished to have as many states as possible attached to him by his kindness toward them. He, therefore, undertakes the affair, and prevails upon the Sequani to allow the Helvetii to march through their territories, and arranges that they should give hostages to each other-the Sequani not to obstruct the Helvetii in their march-the Helvetii, to pass without mischief and outrage.