C. Julius Caesar, Gallic War

These matters being arranged, and Lucterius now checked and forced to retreat, because he thought it dangerous to enter the line of Roman garrisons, Caesar marches into the country of the Helvii; although mount Cevennes , which separates the Arverni from the Helvii, blocked up the way with very deep snow, as it was the severest season of the year; yet having cleared away the snow to the depth of six feet, and having opened the roads, he reaches the territories of the Arverni, with infinite labor to his soldiers. This people being surprised, because they considered themselves defended by the Cevennes as by a wall, and the paths at this season of the year had never before been passable even to individuals, he orders the cavalry to extend themselves as far as they could, and strike as great a panic as possible into the enemy. These proceedings are speedily announced to Vercingetorix by rumor and his messengers. Around him all the Arverni crowd in alarm, and solemnly entreat him to protect their property, and not to suffer them to be plundered by the enemy, especially as he saw that all the war was transferred into their country. Being prevailed upon by their entreaties he moves his camp from the country of the Bituriges in the direction of the Arverni.