Isabella's crown unification and succession arrangements

Timeline

1. 1490Court of Castile · CastileIsabella and Ferdinand formally advanced betrothal negotiations between Prince Juan and Margaret, daughter of the Archduke of Austria, and publicly confirmed Juan as first heir to the joint realm of Castile and Aragon, stabilizing domestic political expectations after the war.
2. 1490Castile · CastileThe royal family designated second daughter Juana as heir after Juan, and made political arrangements for her future marriage to Portugal or the Holy Roman Empire. Clarifying the succession order reduced the nobility's room for maneuvering over the throne.
3. 1490Iberian Peninsula · Iberian PeninsulaIsabella used late-war domestic consolidation to continue centralized governance: coordinating Castilian and Aragonese decision-making in diplomacy, military, and finance, and restricting great nobles' private troops and local judicial privileges. Though the two realms' laws and institutions remained separate, joint rule matured in 1490, paving the way for the later concept of a unified 'Spanish' crown.