the moment, and his marriage with Ealdgyth, the sister of Earls Edwin and Morcar, which may be dated with probability to about this time,  was very possibly intended to conciliate the great midland house. It would certainly serve as a definite assertion that Harold had no intention of fulfilling that part of his oath to William which pledged him to a marriage with the duke's daughter, nor can we doubt that Harold realised the expediency of providing an heir to his crown with the least possible delay. At any rate he seems to have been enjoying a few weeks of tranquillity after his visit to York when he received an unmistakable intimation of the coming storm, which was none the less ominous because its immediate results were insignificant.
Tostig, the dispossessed earl of Northumbria, had spent the winter of 1065-6, as we have seen, with Baldwin of Flanders,  a fact which is suggestive when we remember the relations between Baldwin and William of Normandy. It is evident that Tostig was spending the period of his banishment in forming schemes for his restoration, and the fact that his brother on becoming king dare not or would not recall him made him inevitably a willing tool of William's policy. Accordingly, early in 1066 Tostig moved from Flanders Into Normandy, appeared at the duke's court, and urged him on to an invasion of England. It is quite possible that he was present at the assembly of Lillebonne; one writer goes so far as to say that the arguments of Tostig contributed largely to persuade the Norman nobility to undertake the enterprise,  and William may have derived some little advantage from the fact that he could point to one man of high rank among the English nation as an adherent. But it would seem that Tostig was unwilling to await the development of his host's plans, and in May he set off from the Cotentin on an expedition of his own intended to ravage the English coasts. He landed first in the Isle of Wight, where the inhabitants bought him off with money and provisions, and then sailed, ravaging the coast of Sussex and Kent, until he came to Sandwich. At Sandwich he raised a small force of sailors, but at the same time the news of his expedition was brought to his brother in London, who at once set out for the Kentish coast. Before he could reach Sandwich, however, Tostig had started northward again and finally entered the Humber with sixty ships, harrying the coast of Lindsey. Upon receiving the news Earls Edwin and Morcar, having called out the local fyrd, inarched with it to the Humber and compelled Tostig to take refuge in his ships. At this point Tostig was deserted by the men of Sandwich whom he had impressed, and, his fleet being now reduced to twelve ships, he made his way to Scotland and spent the summer, we are told, with King Malcolm. 
Tostig's futile raid has an interest of its own in the glimpse which it gives us of the English defences just before the Norman invasion. The evidence of Domesday Book shows that an Anglo-Saxon king had some sort of naval force permanently at his disposal, and we know that Harold built and maimed a number of ships to keep the Channel against his Norman rival, but from whatever cause, the English navy in this critical year proved itself miserably ineffective.  A mere adventurer, with no foreign aid of any consequence and no local support in England, Tostig could still spread devastation with impunity along half the English coast. The story of Tostig's expedition reads like a revival of one of the Danish raids of the ninth century the enemy sacks a town, the fyrd are summoned and hurry to the spot to find that the raiders have just left to plunder the nearest unprotected locality. Clearly the coast defences of England, for all the bitter experience of the Danish wars, had made no real advance since the days of Alfred ; and it is not unfair to remark that this fact reflects little credit upon the statesmanship of Harold. He had himself been an exile and had made a bid for power by a piratical descent upon England very similar to the present expedition of Tostig's. I