For the first four centuries after the Norman conquest the part played by Cornwall in England's political history was comparatively unimportant. In her final attempt in 1471 to restore the fortunes of the house of Lancaster, Queen Margaret received the active support of the Cornish, who, under Sir Hugh Courtenay and Sir John Arundell, accompanied her to the fatal field of Tewkesbury, and in 1473 John de Vere, earl of Oxford, held St Michael's Mount in her behalf until the following February, when he surrendered to John Fortescue. A rising of considerable magnitude in 1497 at the instigation of Thomas Flamank, occasioned by the levy of a tax for the Scottish war, was only repelled after the arrival of the insurgents at Blackheath in Kent. Perkin Warbeck, who landed at Whitsand Bay in the parish of Sennen, obtained general support in the same year. The imposition of the Book of Common Prayer and the abrogation of various religious ceremonies led to a rebellion in 1549 under Sir Humphry Arundell of Lanherne, the rebels, who knew little English, demanding the restoration of the Latin service, but a fatal delay under the walls of Exeter led to their early defeat and the execution of their leaders. During the Civil War of the 17th century Cornwall won much glory in the royal cause. In 1643 Sir Ralph Hopton, who commanded the king's Cornish troops, defeated General Ruthen on Bradoc Down, while General Chudleigh, another parliamentary general, was repulsed near Launceston, and the earl of Stamford at Stratton. The whole county was thereby secured to the king. Led by Sir Beville Grenville of Stow the Cornish troops now marched into Somersetshire, where in the indecisive battle of Lansdowne they greatly distinguished themselves, but lost their brave leader. In July 1644 the earl of Essex marched into Cornwall and was followed soon afterwards by the king's troops in pursuit. Numerous engagements were fought, in which the latter were uniformly successful. The troops of Essex were surrounded and their leader escaped in a boat from Fowey to Plymouth. In 1646, owing to dissensions amongst the king's officers, and in particular to the refusal of Sir Richard Grenville to serve under Lord Hopton, and to the defection of Colonel Edgcumbe, the royal cause declined and became desperate. On the 16th of August 1646 articles of capitulation were signed by the defenders of Pendennis Castle.