These operations took two months;[174] the same time had been employed by the Helvetii in negotiating the conditions of their passage through the country of the Sequani, moving from the Rhone to the Saône, and beginning to pass the latter river. They had passed the Pas-de-l’Ecluse, followed the right bank of the Rhone as far as Culoz, then turned to the east through Virieu-le-Grand, Tenay, and Saint-Rambert, and, thence crossing the plains of Ambérieux, the river Ain, and the vast plateau of the Dombes, they had arrived at the Saône, the left bank of which they occupied from Trévoux to Villefranche. (_See Plate 4._) The slowness of their march need not surprise us if we consider that an agglomeration of 368,000 individuals, men, women, and children, dragging after them from 8,000 to 9,000 wagons, through a defile where carriages could only pass one abreast, would necessarily employ several weeks in passing it.[175] Cæsar, no doubt, calculated beforehand, with sufficient accuracy, the time it would take them to gain the banks of the Saône; and we may therefore suppose that, at the moment when he repaired into Italy, he hoped to bring thence his army in time to prevent them from passing that river. He established his camp near the confluence of the Rhone and the Saône, on the heights which command Sathonay; thence he could equally manœuvre on the two banks of the Saône, take the Helvetii in flank as they marched towards that river, or prevent them, if they crossed it, from entering into the Roman province by the valley of the Rhone. It was probably at this point that Labienus joined him with the troops which had been left with him, and which raised to six the number of his legions. His cavalry, composed principally of Ædui and men raised in the Roman province, amounted to 4,000 men. During this time the Helvetii were ravaging the lands of the Ambarri, those of the Ædui, and those which the Allobroges possessed on the right bank of the Rhone. These peoples implored the succour of Cæsar. He was quite disposed to listen to their prayers.[176] [Sidenote: Defeat of the Helvetii on the Saône.]