Analysis of information sources in references of the Wikipedia article "War of succession" in English language version.
Hereditary right lay at the basis of Anglo-Saxon royalty, but it was a hereditary right of the family as a whole, and not specifically any one of its members. (…) In Anglo-Saxon England two considerations seem here to have been particularly influential. The one was the expressed wish of the reigning king respecting his successor within the royal family; the other was the acceptance of an individual (also within the family) by the magnates, and the recognition of reciprocal rights and duties between them as ratified by oath.(1967 reprint)
The extinction of royal lines occasioned prolonged wars of succession, such as the Hundred Years' War in France, the Wars of the Roses in England and the Spanish and Austrian Wars of Succession in the eighteenth century.