Two years after the Norman conquest of England, Exeter rebelled against King William. Gytha Thorkelsdóttir, the mother of the slain King Harold, was living in the city at the time, and William promptly marched west and initiated a siege. After 18 days, William accepted the city's honourable surrender, swearing an oath not to harm the city or increase its ancient tribute. However, William quickly arranged for the building of Rougemont Castle to strengthen Norman control over the area. Properties owned by Saxon landlords were transferred into Norman hands and, on the death of Bishop Leofric in 1072, the Norman Osbern FitzOsbern was appointed his successor.