de bello gallico, 1.6

There were in all two journeys, by which routes they were able to leave their home. One (was) through the Sequani, narrow and difficult, between Mt. Iura and the river Rhodanus, by which scarcely a single line of wagons might be led; moreover, the tallest mountain was hanging over, so that very easily could few prevent (many): the other journey (was) through our province, easier by much and less encumbered, on account of the fact that the Rhodanus river flows between the territories of the Helvetii and the Allobrogi, who recently had been pacified, and this is crossed in not no places by a ford. Genava is last town of the Allobrogi and is closest to the border of the Helvetii. From this town a bridge reaches to the Helvetii. They were thinking that they themselves would persuade the Allobrogi, because they seemed not yet in good spirit towards the Roman populace, or they would compel them by force to allow them to go through their territory. With all these things having been prepared for departure they announced the date they would all convene, five days before the Kalends of April, in the consulship of Lucius Piso and Aullus Gabinus.