With William's return to England began the long and difficult task of bringing the country completely under his control. But this was not a task that called for military genius. Patience was the quality most demanded, and William's patience gave way but rarely. There was no army in the field against him. No large portion of the land was in insurrection. No formal campaign was necessary. Local revolts had to be put down one after another, or a district dealt with where rebellion was constantly renewed. The Scandinavian north and the Celtic west were the regions not yet subdued, and the seats of future trouble. Three years were filled with this work, and the fifteen years that follow were comparatively undisturbed. For the moment after his return, William was occupied with no hostilities. The Christmas of 1067 was celebrated in London with the land at peace, Normans and English meeting together to all appearance with cordial good-will. A native, Gospatric, was probably at this time made Earl of Northumberland, in place of Copsi, who had been killed, though this was an exercise of royal power in form rather than in reality, since William's authority did not yet reach so far. A Norman, Remigius, was made Bishop of Dorchester, in place of Wulfwig, who had died while the king was in Normandy, and William's caution in dealing with the matter of Church reform is shown in the fact that the new bishop received his consecration from Stigand. It is possible also that another heavy tax was imposed at this time.

But soon after Christmas, William felt himself obliged to take the field. He had learned that Exeter, the rich commercial city of the south-west, was making preparations to resist him. It was in a district where Harold and his family had had large possessions. His mother was in the city, and perhaps others of the family. At least some English of prominence seem to have rallied around them. The citizens had repaired and improved their already strong walls. They had impressed foreigners, merchants even, into their service, and were seeking allies in other towns. William's rule had never yet reached into that part of England, and Exeter evidently hoped to shut him out altogether. When the king heard of these preparations, he acted with his usual promptitude, but with no sacrifice of his diplomatic skill. The citizens should first be made to acknowledge their intentions. A message was sent to the city, demanding that the oath of allegiance to himself be taken. The citizens answered that they would take no oath, and would not admit him within the walls, but that they were willing to pay him the customary tribute. William at once replied that he was not accustomed to have subjects on such conditions, and at once began his march against the city. Orderic Vitalis thought it worthy of note, that in this army William was using Englishmen for the first time as soldiers.

When the hostile army drew near to the town, the courage of some of the leading men failed, and they went out to seek terms of peace. They promised to do whatever was commanded, and they gave hostages, but on their return they found their negotiations disavowed and the city determined to stand a siege. This lasted only eighteen days. Some decided advantage which the Normans gained - the undermining of the walls seems to be implied - induced the city to try again for terms. The clergy, with their sacred books and relics, accompanied the deputation, which obtained from the king better promises than had been hoped for. For some reason William departed from his usual custom of severity to those who resisted. He overlooked their evil conduct, ordered no confiscations, and even stationed guards in the gates to keep out the soldiers who would have helped themselves to the property of the citizens with some violence. But as usual he selected a site for a castle within the walls, and left a force of chosen knights under faithful command, to complete the fortification and to form the garrison. Harold's mother, Gytha, left the city before its surrender, and finally found a refuge in Saint Omer, in Flanders. Harold's sons also, if they were in Exeter, made their escape before its fall.

After subduing Exeter, William marched with his army into Cornwall, and put down without difficulty whatever resistance he found there. The confiscation of forfeited estates was no doubt one object of his march through the land, and the greater part of these were bestowed upon his own half brother, Robert, Count of Mortain, the beginning of what grew ultimately into the great earldom of Cornwall. In all, the grants which were made to Robert have been estimated at 797 manors, the largest made to any one as the result of the Conquest. Of these, 248 manors were in Cornwall, practically the whole shire; 75 in Dorset, and 49 in Devonshire. This was almost a principality in itself, and is alone nearly enough to disprove the policy attributed to William of scattering about the country the great estates which he granted. So powerful a possession was the earldom which was founded upon this grant that after a time the policy which had been followed in Normandy, in regard to the great counties, seemed the only wise one in this case also, and it was not allowed to pass out of the immediate family of the king until in the fourteenth century it was made into a provision for the king's eldest son, as it has ever since remained. These things done, William disbanded his army and returned to spend Easter at Winchester.