The usurper's reign was from the first a troubled one. Less than three months after his coronation the first insurrection broke out; it was headed--strangely enough--by the duke of Buckingham, who seems to have been shocked by the murder of the princes; he must have been one of the few who had certain information of the crime. He did not take arms in his own cause, though after the house of York the house of Buckingham had the best claim to the throne, as representing Thomas of Woodstock, the youngest son of Edward III. His plan was to unite the causes of York and Lancaster by wedding the Lady Elizabeth, the eldest sister of the murdered princes, to Henry Tudor, earl of Richmond, a young exile who represented the very doubtful claim of the Beauforts to the Lancastrian heritage. Henry was the son of Margaret Beaufort, the daughter of John, first duke of Somerset, and the niece of Edmund, second duke, who fell at St Albans. All her male kinsmen had been exterminated in the Wars of the Roses.

This promising scheme was to be supported by a rising of those Yorkists who rejected the usurpation of Richard III., and by the landing on the south coast of Henry of Richmond with a body of Lancastrian exiles and foreign mercenaries. But good organization was wanting, and chance fought for the king. A number of scattered risings in the south were put down by Richard's troops, while Buckingham, who had raised his banner in Wales, was prevented from bringing aid by a week of extraordinary rains which made the Severn impassable. Finding that the rest of the plan had miscarried, Buckingham's retainers melted away from him, and he was forced to fly. A few days later he was betrayed, handed over to the king, and beheaded (Nov. 2, 1483). Meanwhile Richmond's little fleet was dispersed by the same storms that scattered Buckingham's army, and he was forced to return to Brittany without having landed in England.

Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 5 — Part 148

Here King Richard's luck ended. Though he called a parliament early in 1484, and made all manner of gracious promises of good governance, he felt that his position was insecure. The nation was profoundly disgusted with his unscrupulous policy, and the greater part of the leaders of the late insurrection had escaped abroad and were weaving new plots. Early in the spring he lost his only son and heir, Edward, prince of Wales, and the question of the succession to the crown was opened from a new point of view. After some hesitation Richard named his nephew John de la Pole, earl of Lincoln, a son of his sister, as his heir. But he also bethought him of another and a most repulsive plan for strengthening his position. His queen, Anne Neville, the daughter of the kingmaker, was on her death-bed. With indecent haste he began to devise a scheme for marrying his niece Elizabeth, whose brothers he had murdered but a year before. Knowledge of this scheme is said to have shortened the life of the unfortunate Anne, and many did not scruple to say that her husband had made away with her.

Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 5 — Part 148