his brother Richard were killed, probably between July to September 1483; debate on who gave the orders, and why, continues, although their uncle Richard III was the beneficiary. By mid-August, Elizabeth Woodville was certain of the deaths of her sons; after her initial grief turned to fury, she opened secret talks with Margaret Beaufort. She promised her support in return for Henry's agreement to marry her eldest daughter Elizabeth. In December 1483, Henry swore an oath to do so, which he duly carried out after his coronation in October 1485. Prior to his succession, Richard III declared his nephews illegitimate, on the grounds his brother's marriage to Elizabeth Woodville was invalid. The Titulus Regius argued that since Edward had agreed to marry Lady Eleanor Talbot, his marriage to Elizabeth Woodville was void. Both Eleanor and Edward were dead, but Robert Stillington, Bishop of Bath and Wells, further claimed to have actually carried out the ceremony. Once secure on the throne Henry VII annulled the Titulus and arrested Stillington, since his marriage to Elizabeth's daughter added legitimacy to his claim; Stillington died in prison in 1491. Despite this apparent resolution, the Yorkist cause continued well into the 16th century. The most famous are the pretenders Lambert Simnel and Perkin Warbeck, but Yorkist challengers remained a concern for Henry VII and his son. In 1541, Henry VIII executed Margaret Pole, Countess of Salisbury, daughter of the Duke of Clarence, while a number of attempts were made on the life of her son, Cardinal Reginald Pole, who died in 1558. Genealogical table See also List of earls in the reigns of Henry VI and Edward IV of England Notes References Sources Further reading External links Edward IV at BBC History British Library Catalogue of Illuminated Manuscripts (SEARCH: Keyword Edward IV, Start year 1470, End year 1480 for details and images of Edward IV's manuscripts). 1442 births 1483 deaths 15th-century English monarchs 15th-century English nobility Burials at St George's Chapel, Windsor Castle Dukes of York English pretenders to the French throne English people of French descent Plantagenet 03 Plantagenet Knights of the Golden Fleece People from Rouen People of the Hundred Years' War Earls of Cambridge