But though Britain may have flourished in material prosperity under Carausius, no Roman emperor could have allowed his rebellious acts to remain unchastised, and hence, after a long preparation, Constantius was sent to England with a powerful force, and in a short space of time restored the imperial sway; not the less easily, perhaps, that Carausius had in the meanwhile been murdered by his lieutenant Allectus. No mention is made of the number of ships or troops constituting the expedition of Constantius, but it must have been on an extensive scale, as it captured in its first attempt the port of Boulogne, with part of the British fleet.[460] [Sidenote: Welsh and Scots, A.D. 360.] [Sidenote: Saxons, A.D. 364.] [Sidenote: Their ships.] Nor do historians afford much information with regard to the affairs of Britain from the death of Constantius, father of Constantine the Great, until more than fifty years afterwards, when its Roman subjects were seriously harassed by the Welsh on the west, and the Caledonians on the north, who ravaged the frontiers and spread terror throughout the now civilized provinces of Britannia Romana. Nor was this all: while harassed by the descendants of the Celts, the Germanic Saxons invaded England on the east and south, startling the Romans and their subjects by the daring intrepidity with which they skimmed over the roughest seas in “boats of leather,” and, without respect of persons or property, plundered and carried off everything worthy of removal. Besides these frail craft the Saxons, however, possessed more than one description of vessel altogether superior to their leather-covered boats, called by the old historians in Latin, _Kiulæ_; in Saxon, _Ceol_, or _Ciol_; and in English, _Keels_.[461] Some writers also maintain that they had strong open boats adapted to warfare at sea. That these German rovers possessed larger vessels than even their war-galleys is ascertained by the fact that, within seventy or eighty years after they first gained a secure footing in Britain, they received a reinforcement of “five thousand men, in seventeen ships,”[462] or at the rate of about three hundred men to a ship, besides provisions, stores, and munitions of war. But of their form, size, or equipment no accounts have been preserved, and it can, therefore, tend to no useful purpose to attempt, as Mr. Strutt has done, the reproduction of the supposed types of the vessels of Canute, as all such drawings are only the creations of fancy.