Manuel I of Portugal
Manuel's mother was the granddaughter of King John I of Portugal, whereas his father was the second surviving son of King Edward of Portugal and the younger brother of King Afonso V of Portugal. In 1495, Manuel succeeded his first cousin, King John II of Portugal, who was also his brother-in-law, as husband to Manuel's sister, Eleanor of Viseu.
War of the Portuguese Succession
Ranuccio Farnese (1569–1622), the hereditary Duke of Parma and Piacenza, was the son of the late elder daughter of Duarte of Portugal, Duke of Guimarães, the only son of Manuel I whose legitimate descendants survived at that time, Ranuccio was according to the feudal custom the first heir to the throne of Portugal. He was the son of Don Alexander Farnese, Duke of Parma and Piacenza and of Maria of Portugal. His great-uncle Henry I of Portugal's death triggered the struggle for the throne of Portugal when Ranuccio was 11 years old. However, his father was an ally and even a subject of the Spanish King, another contender, so Ranuccio's rights were not very forcibly claimed at that time. Ranuccio became reigning Duke of Parma in 1592.