In William the Conqueror's time Githa, the mother of Harold, gave the Normans considerable trouble. It was only on the appearance of that monarch before the city's walls that the citizens surrendered. They were made to pay a heavy fine, whilst Githa escaped with her treasures to take refuge in Flanders. William in the end relented and renewed all their former privileges. Nevertheless he took the precaution to erect a fortress in Exeter, the charge of which was entrusted to Baldwin de Brioniis, who, by virtue of his office, became Earl of Devon and sheriff of the county. The chief remains of the Castle is a gateway tower.

This same castle was held by the partisans of the Empress Matilda for three months, when it was compelled in 1136 through scarcity of water to surrender to Stephen. Contrary to expectation, they were treated very well. Henry II., for their loyalty, was pleased to grant additional privileges.

In 1200 the city for the first time was governed by a mayor and corporation. Subsequently their importance was increased by the charters of Edward III., Edward IV., and Henry VIII., whilst Henry VIII. constituted Exeter a county of itself. These privileges were extended by Charles I.; and in 1684 a new charter of incorporation was granted by Charles II., but not put into effect. In 1770 George III. renewed and confirmed the charter, since when the government has been invested in a mayor assisted by subordinate officers. In the meantime a curious incident occurred in 1824, which greatly interfered with the prosperity of the city, inasmuch as the navigation of the river Exe was obstructed by a dam erected by Hugh Courtenay, at that time Earl of Devon.

Exeter, through its happy situation on the river Exe, had for many years reaped full benefit. At the time of the Conquest it had gained considerable importance through the river being navigable for ships right up to its quays. Among many petty matters that annoyed the Earl the following is alleged to have been the chief. There were three pots of fish in the market-place. The Earl wanted them all. The Bishop likewise. Neither would give way, and the Mayor was called in to adjudicate. He allotted one to the Earl, the second to the Bishop, and the third to the town. This distribution did not suit the Earl. Out of pique he caused a dam to be constructed across the Exe at Topsham. There he built a quay, and had the satisfaction of greatly curtailing the trade of Exeter.

In 1286 Edward I. assembled a parliament at Exeter, whilst in 1371 the Black Prince brought here his royal prisoner of France and stayed several days. The Duchess of Clarence, accompanied by many royal adherents, took refuge within the city walls in 1469. It was besieged by Sir William Courtenay, who eventually raised it on the mediation of the clergy.

The next event of importance not only affected Exeter, but threw into agitation the whole of the British Empire. Of two impostors that laid claim to the Crown which Henry VII. was wearing, the second was a youth called Perkin Warbeck. He bore such a striking resemblance to the Plantagenets that he had been secretly instructed to impersonate Richard Duke of York, the younger brother of Edward V., who it was pretended had escaped from the Tower and from the fate that overtook his brother. So ingratiating was his manner that he successfully enlisted the aid of the Duchess of Burgundy, who was holding her court at Brussels. His first attempt to land in England was in Kent; his second in Ireland. Both ventures being unsuccessful, he tried Scotland. There he convinced King James IV. that he was a true Plantagenet, and through him he raised an army and invaded England. However, the two kings having come to an understanding, Warbeck retired to Ireland. He there received an invitation from the Cornishmen, acting on which he landed at Whitsand Bay in that county.

At Bodmin he was joined by a considerable force of men, with whom he marched and laid siege to Exeter in the year 1497. At the approach of the royal forces his followers were dispersed, whilst he fled to Beaulieu in Hampshire. Two years afterwards he ended his career at Tyburn.