On the following morning, just as the victorious leader was about to re-commence his march, news arrived from the camp that a violent tempest had seriously damaged the fleet. Many of his vessels were wrecked, and others rendered unfit for service. Like a prudent general, Cæsar at once returned to the camp, to assure himself of the extent of the injury done to his fleet, and found it more considerable than he imagined. Forty vessels were lost; the rest could be repaired, though not without great labour and time. Every artificer in his army was set to work; others were sent for from the continent; and instructions written to Labienus in Gaul to construct new galleys to replace those which were lost. The next step was worthy the genius and reputation of Cæsar. After having repaired his ships, he caused his legions to draw them out of reach of the tide, high up on the shore, and enclosed the whole of them in a fortified camp--an immense work, when we consider that it was executed in an enemy's country, and the scanty means at his command for such an undertaking. Meanwhile the Britons had united under Cassivelaunus, head-king of the tribes north of the Thames, and Cæsar advanced to meet him. The king proved a doughty opponent, seldom venturing upon a pitched battle, but harassing the Romans by sudden attacks, in which the chariots proved particularly formidable. At length Cæsar managed, with difficulty, to cross the Thames somewhere above London, and ravaged the king's territory. Fortunately the powerful tribe of the Trinobantes, who inhabited part of Middlesex and Essex, came over to him at this juncture, having old scores to pay off against Cassivelaunus, and they were followed by other tribes. Cæsar was therefore able to storm Verulam, the stronghold of the British king, and then, finding that his camp on the coast was being besieged by the four kings of Kent, that his troops were being wearied out by the constant alarms, and having, in addition, received unpleasant news from Gaul, he accepted the offers of peace made by Cassivelaunus, and departed. So ended Cæsar's invasions of Britain.