The position of York as heir presumptive to the crown by descent from Edmund of Langley had ceased with the birth of a son to Henry; but the victory of Northampton no sooner raised him to the supreme control of affairs than he ventured to assert the far more dangerous claims which he had secretly cherished, and to their consciousness of which was owing the bitter hostility of Henry and his Queen. As the descendant of Edmund of Langley he stood only next in succession to the House of Lancaster, but as the descendant of Lionel, the elder brother of John of Gaunt, he stood in strict hereditary right before it. We have already seen how the claims of Lionel had passed to the House of Mortimer: it was through Anne, the heiress of the Mortimers, who had wedded his father, that they passed to the Duke. There was, however, no constitutional ground for any limitation of the right of Parliament to set aside an elder branch in favour of a younger, and in the Parliamentary Act which placed the House of Lancaster on the throne the claim of the House of Mortimer had been deliberately set aside. Possession, too, told against the Yorkist pretensions.

To modern minds the best reply to their claim lay in the words used at a later time by Henry himself. "My father was King; his father also was King; I myself have worn the crown forty years from my cradle; you have all sworn fealty to me as your sovereign, and your fathers have done the like to mine. How then can my right be disputed?" Long and undisturbed possession, as well as a distinctly legal title by free vote of Parliament, was in favour of the House of Lancaster. But the persecution of the Lollards, the interference with elections, the odium of the war, the shame of the long misgovernment, told fatally against the weak and imbecile King, whose reign had been a long battle of contending factions. That the misrule had been serious was shown by the attitude of the commercial class. It was the rising of Kent, the great manufacturing district of the realm, which brought about the victory of Northampton. Throughout the struggle which followed, London and the great merchant towns were steady for the House of York. Zeal for the Lancastrian cause was found only in Wales, in northern England, and in the south-western shires.

It is absurd to suppose that the shrewd traders of Cheapside were moved by an abstract question of hereditary right, or that the wild Welshmen believed themselves to be supporting the right of Parliament to regulate the succession. But it marks the power which Parliament had now gained that the Duke of York felt himself compelled to convene the two Houses, and to lay his claim before the Lords as a petition of right. Neither oaths nor the numerous Acts which had settled and confirmed the right to the crown in the House of Lancaster could destroy, he pleaded, his hereditary claim. The baronage received the petition with hardly concealed reluctance, and solved the question, as they hoped, by a compromise. They refused to dethrone the King, but they had sworn no fealty to his child, and at Henry's death they agreed to receive the Duke as successor to the crown. But the open display of York's pretensions at once united the partizans of the royal House, and the deadly struggle which received the name of the Wars of the Roses, from the white rose which formed the badge of the House of York and the red rose which was the cognizance of the House of Lancaster, began in the gathering of the North round Lord Clifford, and of the West round the new Duke of Somerset. York, who had hurried to meet the first with a far inferior force, was defeated and slain at Wakefield, and the passion of civil war broke fiercely out on the field.

The Earl of Salisbury was hurried to the block, and the head of Duke Richard, crowned in mockery with a diadem of paper, is said to have been impaled on the walls of York. His second son, Lord Rutland, fell crying for mercy on his knees before Clifford. But Clifford's father had been the first to fall in the battle of St. Albans which opened the struggle. "As your father killed mine," cried the savage baron while he plunged his dagger in the young noble's breast, "I will kill you!" The brutal deed was soon to be avenged. Duke Richard's eldest son, Edward, Earl of March, hurried from the West, and, routing a body of Lancastrians at Mortimer's Cross, struck boldly upon London. A force of Kentishmen under the Earl of Warwick barred the march of the Lancastrian army on the capital, but after a desperate struggle at St. Albans the Yorkist forces broke under cover of night. An immediate advance of the conquerors might have decided the contest, but Queen Margaret paused to sully her victory by a series of bloody executions, and the rough northerners who formed the bulk of her army scattered to pillage, while Edward appeared before London. The citizens rallied at his call, and cries of "Long live King Edward" rang round the handsome young leader as he rode through the streets.

A council of Yorkist lords, hastily summoned, resolved that the compromise agreed on in Parliament was at an end and that Henry of Lancaster had forfeited the throne. The final issue, however, now lay, not with Parliament, but with the sword. Disappointed of London, the Lancastrian army fell rapidly back on the North, and Edward hurried as rapidly in pursuit.

The two armies encountered one another at Towton Field, near Tadcaster. In the numbers engaged, as well as in the terrible obstinacy of the struggle, no such battle had been seen in England since the fight of Senlac. The armies numbered together nearly 120,000 men. The day had just broken when the Yorkists advanced through a thick snow-fall, and for six hours the battle raged with desperate bravery on either side. At one critical moment Warwick saw his men falter, and stabbing his horse before them, swore on the cross of his sword to win or die on the field. The battle was turned by the arrival of Norfolk with a fresh force. At last the Lancastrians gave way, a river in their rear turned the retreat into a rout, and the flight and carnage, for no quarter was given on either side, went on through the night and the morrow. Edward's herald counted more than 20,000 Lancastrian corpses on the field, and the losses of the conquerors were hardly less heavy. But their triumph was complete. The Earl of Northumberland was slain; the Earls of Devonshire and Wiltshire were taken and beheaded; the Duke of Somerset fled into exile.