It was one thing to make a vague promise which he did not feel bound to keep. It was quite a different matter to swear solemnly on the relics of saints and martyrs. For in those days to break a promise so sworn was counted a deadly sin. On the cover of cloth of gold two small caskets were laid. With slow, unwilling steps Harold drew near to them. They were very small. After all, he thought, an oath sworn upon such small relics might not be very binding. To break such an oath might not be very wicked.
Yet as he stood there he shuddered. His hands trembled as he laid them upon the little caskets, and in a low and troubled voice swore his oath. As the last words died away all the nobles cried out, “God grant it.” Harold knelt to kiss the caskets. Then, as he rose from his knees, at a sign from Duke William, the cover was removed from the chest. Of a sudden Harold saw upon what holy relics he had sworn. As he gazed upon the pile he shuddered and turned pale. How was it possible, he asked himself, to break such an oath and yet save his soul. William had now got all he wanted from his captive guest and he allowed him to go home. He rode with Harold to the seashore, kissed him upon either cheek, and bade him be faithful to his oath. Then, greatly rejoicing, he turned homeward again.*
From ‘A History of France’ (1912) by Henrietta Elizabeth Marshall (1867-1941).
* The only contemporary support for this tale comes from William of Poitiers, who was William of Normandy’s personal chaplain. It was depicted on the Bayeux Tapestry, but that was commissioned by William. It was subsequently repeated by various writers in France and England, but in widely divergent forms. Neither the Anglo-Saxon Chronicle nor any other English (i.e. not Norman) source of the time hints at it. The only witness who was not a Norman was Harold, and he was dead: but see The Hermit of Handbridge.