This _Requiescat_ of the monk of Peterborough has carried us forward half a century, till the Conqueror, in the full maturity of his power and strength, rode to his death down the steep street of the burning town of Mantes and was buried in his own great abbey-church at Caen. And the good peace that he gave the land at the end came, both in Normandy and in England, only after many stormy years of war, rebellion, and strife. William was but sixty when he died; when his father was laid away in the basilica of far-off Nicæa, he was only seven or at most eight. The conquest of England was made in his fortieth year, when he had already reigned thirty-one years as duke. Or, if we deduct the years of his youth, the conquest of England falls just halfway between his coming of age and his death. I give these figures to adjust the perspective. William’s place in the line of English kings is so prominent and his achievements in England are so important that they always tend to overshadow in our minds his earlier years as duke. Yet without these formative years there could have been no conquest of England, and without some study of them that conquest cannot be understood. If we pass over rapidly, as for lack of information we must needs do, the dozen years of William’s minority, we find his reign in Normandy chiefly occupied with his struggles with his vassals, his neighbors, and the king of France, all a necessary consequence of his feudal position as duke. The Norman vassals, always turbulent and rebellious, seem to have broken forth anew upon the death of Robert the Magnificent, and such accounts as have reached us of the events of the next twelve years reveal a constant state of anarchy and disorder. The revolt of the barons came to a head in 1047, when the whole of Lower Normandy rose under the leadership of the two chief _vicomtes_ of the region, Ranulf of Bayeux and Néel of Saint-Sauveur, the ruins of whose family castle of Saint-Sauveur-le-Vicomte still greet the traveller who leaves Cherbourg for Paris. William, who was hunting in the neighborhood of Valognes, was obliged to flee half-clad in the night and to pick his way alone by devious paths across the enemy’s country to his castle of Falaise. With the assistance of the French king he was able to collect an army from Upper Normandy and meet the rebels on the great plain of Val-des-Dunes, near Caen, where the _Mont-joie_ of the French and the _Dex aie_ of the duke’s followers answered the barons’ appeals to their local saints of St. Sauveur, St. Sever, and St. Amand. William was victorious; the leaders of the revolt were sent into exile, but one of them, Grimoud of Plessis, the traitor, apparently he who had sought William’s death in the night at Valognes, was put in prison at Rouen in irons which he wore until his death.