John I of Castile

Timeline

1. 1371–1379Toledo · Castilla-La ManchaAs eldest son of Henry II, he received administrative and military training at the Castilian court in the 1370s, participating in his father's policies toward Portugal and domestic remnant opposition, preparing for succession.
2. 1379–1380Burgos · CastileAfter Henry II died in 1379, John I formally succeeded, immediately consolidating the Trastámara noble alliance and continuing diplomatic arrangements with Portugal and Aragon, laying the foundation for his later claim to the Portuguese throne.