C. Julius Caesar, Gallic War

These things being achieved, while Caesar had every reason to suppose that Gaul was reduced to a state of tranquillity, the Belgae being overcome, the Germans expelled, the Seduni among the Alps defeated, and when he had, therefore, in the beginning of winter, set out for Illyricum , as he wished to visit those nations, and acquire a knowledge of their countries, a sudden war sprang up in Gaul. The occasion of that war was this: P. Crassus, a young man, had taken up his winter quarters with the seventh legion among the Andes, who border upon the [Atlantic] ocean. He, as there was a scarcity of corn in those parts, sent out some officers of cavalry, and several military tribunes among the neighbouring states, for the purpose of procuring corn and provision; in which number T. Terrasidius was sent among the Esubii; M. Trebius Gallus among the Curiosolitae; Q. Velanius, T. Silius, amongst the Veneti.