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.
History of Portugal (1640–1777)
This situation culminated in a revolution by the Portuguese nobility and high bourgeoisie on 1 December 1640, 60 years after the crowning of Philip I. The revolution was planned by Antão Vaz de Almada, Miguel de Almeida and João Pinto Ribeiro. They, together with several associates, killed Secretary of State Miguel de Vasconcelos and imprisoned the king's cousin, the Duchess of Mantua, who had governed Portugal in his name. The moment was well chosen, as Spain was fighting the Thirty Years' War and also facing the Catalan Revolt at the time.
The support of the people became apparent almost immediately and soon John, 8th Duke of Braganza, was acclaimed King of Portugal throughout the country as John IV. By December 2, 1640, John was already sending a letter as sovereign of the country to the Town Hall of Évora.