C. Julius Caesar, Gallic War

When several days had elapsed in winter quarters, and he had ordered corn to be brought in he was suddenly informed by his scouts that all the people had gone off in the night from that part of the town which he had given up to the Gauls, and that the mountains which hung over it were occupied by a very large force of the Seduni and Veragri. It had happened for several reasons that the Gauls suddenly formed the design of renewing the war and cutting off that legion. First, because they despised a single legion, on account of its small number, and that not quite full (two cohorts having been detached, and several individuals being absent, who had been dispatched for the purpose of seeking provision); then, likewise, because they thought that on account of the disadvantageous character of the situation, even their first attack could not be sustained [by us] when they would rush from the mountains into the valley, and discharge their weapons upon us. To this was added, that they were indignant that their children were torn from them under the title of hostages, and they were persuaded that the Romans designed to seize upon the summits of the Alps , and unite those parts to the neighboring province [of Gaul], not only to secure the passes, but also a constant possession.