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.
House of Braganza
João I's tenure as Duke was one intertwined with controversy and intrigue. Having been married to Infanta Catarina, daughter of Infante Duarte, Duke of Guimarães, and thus a grandchild of King Manuel I, during the succession crisis of 1580, the couple pressed their claims to the Portuguese throne. Though Infanta Catarina was a popular claimant, her Habsburg cousin was eventually crowned Philip I of Portugal and the Iberian Union was established. In an attempt at reconciliation with the Brigantine House, King Philip I renewed the title of Constable of Portugal, which João I had held previously, to the Duke's first son, Teodósio II, alongside other title and land grants to the Duke and the House.