The Gauls were embittered at being forced to feed the Roman troops over the winter. The Romans sent out officers to requisition grain from the Veneti, a group of tribes in northwest Gaul, but the Veneti had other ideas and captured the officers. This was a calculated move: they knew this would anger Rome and prepared by allying with the tribes of Armorica, fortifying their hill settlements, and preparing a fleet. The Veneti and the other peoples along the Atlantic coast were versed in sailing and had vessels suitable for the rough waters of the Atlantic. By comparison, the Romans were hardly prepared for naval warfare on the open ocean. Rome was a feared naval power in the Mediterranean, but there the waters were calm, and flimsier ships could be used. Regardless, the Romans understood that to defeat the Veneti they would need a fleet: many of the Venetic settlements were isolated and best accessible by sea. Decimus Brutus was appointed prefect of the fleet.