Two nations, the Tigurini and the Helvetii, made an incursion into the Roman province of Gaul. When Cæsar heard of this movement he built a wall along the river Rhone about a hundred and fifty stades in length to intercept them. When they sent ambassadors to him to endeavor to make a treaty, he ordered them to give him hostages and money. They replied that they were accustomed to receive these things, not to give them. As he wished to prevent them from forming a junction he sent Labienus against the Tigurini, who were the weaker, while he marched against the Helvetii, taking with him about 20,000 Gallic mountaineers. The work was easy to Labienus, who fell upon the Tigurini unawares on the river bank, defeated them, and scattered the greater part of them in disorderly flight.