Though the Earl of Westmoreland adhered to the house of Lancaster the alliance of the other Nevilles would of itself have rendered York formidable; and, besides the Nevilles, there were many feudal magnates who shared York's antipathy to Somerset. Thomas, Lord Stanley, who had married Warwick's sister; John Mowbray, Duke of Norfolk, descended from a granddaughter of the first Edward; John De Vere, Earl of Oxford, whose ancestors had been great in England since the Conquest; and Thomas Courtenay, Earl of Devon, whose pedigree dated from the age of Charlemagne, could not witness without indignation the domination of Beauforts. "We are unwilling," such men must have murmured, "to see the court of Westminster converted into a sty for the brood of Katherine Swynford." York, for some time, hesitated to strike a blow; but, at length, and not without reason, he lost all patience. Indeed, the Yorkists affirmed that a plot had been formed for imprisoning their chief, and putting him secretly to death; and the memory of Humphrey of Gloucester's fate rendered people credulous of any such report. To baffle any such criminal project, a movement against Somerset was resolved upon by the partisans of the White Rose; and, about the opening of 1452, York repaired to his castle of Ludlow, gathered an army among the retainers of the house of Mortimer, and, declaring that he had no evil intentions against the king, to whom he offered to swear fealty on the sacrament, commenced his march toward London. The Lancastrians were alarmed at the intelligence that the duke was in arms; and forces were mustered to intercept his march. But while the royal army went westward by one road York came eastward by another, and, with several thousand men at his back, appeared at the gates of London. The metropolis, however, had aided in that revolution which placed Henry of Bolingbroke on the throne, and still continued well affected to the house of Lancaster. York did not, therefore, meet with such a reception as his friends could have wished. The gates, in fact, were shut in his face; and, not wishing to exasperate the citizens by acts of violence, he marched up the banks of the Thames, crossed the river at Kingston, and, having been joined by the Earl of Devon, encamped his army on Brent Heath, near Dartford. Henry, meantime, ventured on taking the field, and pitched his pavilion on Blackheath. It soon appeared, however, that on neither side was there any inclination to involve the country in civil war. Negotiations were therefore opened; and two bishops, commissioned to act for the king, proceeded to the camp of the Yorkists and demanded of their chief why he had appeared in arms.