It is impossible to fix the date of this campaign; indeed there may have been more than one expedition against Brittany. Still more difficult is it to learn any thing that is undisputed about the famous oath that Harold gave to William, and was afterward so completely punished for breaking. Yet, while we do not know exactly what the oath was, [Pg267] Harold's most steadfast upholders have never been able to deny that there was an oath, and there is no contradiction, on the English side, of the whole affair. His best friends have been silent about it. The most familiar account is this, if we listen to the Norman stories: Harold entered into an engagement to marry one of William's daughters, who must have been very young at the time of the visit or visits to Normandy, and some writers claim that the whole cause of the quarrel lay in his refusal to keep his promise. There is a list beside of what appears to us unlikely concessions on the part of the English earl. Harold did homage to the duke, and formally became his man, and even promised to acknowledge his claim to the throne of England at the death of the Confessor. More than this, he promised to look after William's interest in England, and to put him at once into possession of the Castle of Dover, with the right of establishing a Norman garrison there. William, in return, agreed to hold his new vassal in highest honor, giving him by and by even the half of his prospective kingdom. When this surprising oath was taken, Harold was entrapped into swearing upon the holiest relic of Norman saints which had been concealed in a chest for the express purpose. With the superstitious awe that men of his time felt toward such emblems, this not very respectable act on William's part is made to reflect darkly upon Harold. Master Wace says that "his hand trembled and his flesh quivered when he touched the chest, though he did not know what was in it, and how much more distressed he was when he [Pg268] found by what an awful vow he had unwittingly bound his soul." So Harold returned to England the duke's vassal and future son-in-law, according to the chronicles, but who can help being suspicious, after knowing how Harold was indebted to the duke and bound with cunningly contrived chains until he found himself a prisoner? William of Poitiers, a chronicler who wrote in the Conqueror's day, says that Harold was a man to whom imprisonment was more odious than shipwreck. It would be no wonder if he had made use of a piece of strategy, and was willing to make any sort of promise simply to gain his liberty.