Those who are familiar with the terrible tides and treacherous coast of northern France[33] will readily understand how such able Viking-like ships as the Veneti possessed, appealed to the Romans with their fast but unsuitable craft. The difference would be that between the smart Thames skiff and the tubby though seaworthy dinghy of a North Sea fishing smack. For we know pretty accurately now, thanks to the Althiburus mosaics referred to in the previous chapter, just what Cæsar’s craft were like. Hitherto we have known them as _naves actuariæ_—that is, light vessels of surpassing speed. But if the reader will refer back to Fig. 24 he will find that the _navis actuaria_, whilst propelled both with oars and sail, was nevertheless not much of a ship to be caught in off the rocks and narrow channels in a breeze of wind. Although these _actuariæ_ were neither freight ships (_onerariæ_) nor war-vessels properly speaking, yet they still possessed rams and were used on this expedition for a war-like purpose. There cannot be much doubt that the Veneti had obtained their design and ideas of shipbuilding from the Norsemen who relentlessly swept down from their colder climes and plundered and pillaged from one end of the coast of Northern Europe to the other. As we shall see presently, this design was prevalent for many years before Cæsar came, and as we shall also see from the following chapter it had altered but little at the time when William the Conqueror left the French shores for England in the eleventh century.