Proximity of blood, or proximity by degree of kinship, is one of the ways to determine hereditary succession based on genealogy. In effect, the application of this rule is a refusal to recognize the right of representation, a component of primogeniture. In some feudal entities, proximity of blood was a generally accepted principle. For example, according to the "ancient custom" () in the Duchy of Burgundy, a grandson could not take precedence over a son or daughter , and it was not even clear whether the ruler's grandson could claim precedence over the ruler's brother. Examples Proximity of blood and primogeniture were at loggerheads in numerous medieval succession disputes. Successful applications When Richard the Lionheart died in 1199, the succession to the English throne, as well as to Normandy and Anjou, was disputed between his fourth but sole surviving brother, John, and his nephew Arthur (the son of his second brother, Geoffrey). The Angevin law favored primogeniture and thus Arthur, while the Norman law recognized the proximity of blood and gave precedence to John. Arthur's claim had been recognized by Richard in 1191, but just before his death Richard expressed support for John, who in the end prevailed. Alfonso X of Castile wished to enforce primogeniture by the Siete Partidas in the late 1270s and bequeath his crown to Alfonso, the son of his deceased eldest son, Ferdinand. His second but eldest surviving son, Sancho, rebelled with the support of the nobility and successfully claimed the crown by degree of kinship. In 1307 a dispute erupted over the County of Artois between Mahaut, who had succeeded her father, Robert II, in 1302, and Mahaut's nephew, Robert. Robert II had outlived his son, Philip, and Mahaut put herself forward as "the closest relative to our said father at the time of his death, the reason of propinquity or proximity being notorious in custom". Her nephew, Philip's son, insisted on "representation of our aforesaid father who was the first born of our same grandfather". His appeal was rejected in 1309 on the basis that the established custom of Artois favored Mahaut, but he never relinquished his claim. Odo IV, Duke of Burgundy, having outlived his son Philip, decreed in his will in 1348 that he should be succeeded by his grandson, also named Philip, unless Odo fathered another son. Odo's grandson, however, should have precedence over any daughters Odo might have and