All the hereditary provinces of William were convulsed by this war, and he was at last compelled to draw an army from England to assist him. These forces, led by his ancient captains, soon enabled him to drive Robert and his adherents from their strongholds, and re-establish his authority; the rebellious son himself being driven to seek a retreat in the castle of Gerberoi, which the King of France, who had secretly fomented these dissensions, placed at his disposal. In this fortress he was closely besieged by his angry father, and many encounters took place in the sorties made by the garrison. In one of these Robert engaged the king without knowing him, wounded him in the arm, and unhorsed him. On William calling out for assistance, his son recognised his voice, and, filled with horror at the idea of having so nearly become a parricide, threw himself at his feet, and asked pardon for his offences. So says Florence of Worcester, while other accounts represent William as having been rescued by his attendants. The entreaties of the queen, and other influences, soon afterwards brought about a reconciliation; but it is thought the Conqueror in his heart never forgave his son, although he afterwards took Robert to England. This occurred previous to the expedition recorded on the preceding page, in which he sent his son to oppose the King of Scotland.
The tranquillity which now ensued gave William leisure to begin an undertaking which proves the comprehensive nature of his talents. This was a general survey of all the lands in the kingdom in 1081; their extent in each district; their proprietors, tenures, value; the quantity of meadow, pasture, wood, and arable land which they contained; and in some counties the number of tenants, cottagers, and slaves of all denominations who lived on them. He appointed commissioners for this purpose, who entered every particular in their register by the verdict of juries, and after a labour of six years (for the work was so long in finishing), brought him an exact account of all the landed property in England. This monument, called Domesday Book--the most valuable piece of antiquity possessed by any nation--is still preserved in the Exchequer. It was followed by a great Witena-gemot at Salisbury, attended, it is said, by some sixty thousand men, who all swore obedience to the king "against all other men."