direct assaults At some stage in the battle, Gytha escaped from city by boat along the River Exe, together with some of her supporters, indicating that William's army was not supported by ships. Orderic states that William eventually managed to breach the walls by mining, the first record of this technique being used in England. However, the siege ended by negotiation rather than conquest; according to Orderic, the gates were opened and the townspeople, preceded by their clergy carrying sacred books and relics, pleaded for clemency. All the sources agree that William's terms were generous, in return for the city's fealty, with the Chronicle adding that he agreed to their previous request to pay tax only at pre-Conquest levels. William also prevented his soldiers from claiming their traditional right of looting the surrendered city, posting reliable guards at the gates to ensure its safety. Aftermath William ordered the construction of a stone castle to dominate Exeter and Rougemont Castle was built inside the northeast of the city wall. William's unusual generosity of terms at Exeter may have been due to the need to bring the West Country under his control. Antiquary William Hals speculated that Cadoc, the pre-Conquest Earl of Cornwall who had sworn fealty to William for his earldom, may have supported the rebels at Exeter, and was deprived of his earldom for this. In any case, William subsequently marched his army into Cornwall in a show of strength, before returning to Winchester to celebrate Easter. The garrison of Exeter was initially commanded by William de Vauville but soon passed to Baldwin FitzGilbert (or de Meulles), while Brian of Brittany was made earl of the West Country. Gytha and her entourage sailed from the siege at Exeter to the Bristol Channel where she established a base on the island of Flat Holm, possibly in the hope of a rendez-vous with her grandsons' expedition from Ireland. Eventually, she went to Saint-Omer in Flanders, where she had earlier been exiled with her husband Godwin, Earl of Wessex in 1051. She never returned to England. The sons of Harold did not arrive until later in the year; the citizens of Bristol closed their gates to them and they were later defeated at Bleadon by the English earl Eadnoth the Staller, who was killed in the action. A second incursion into Devon was mounted by Harold's sons in 1069, this time from the