John I, King (Kingdom of Castile (Military Occupation)) : All Data

John I was the King of Castile from 1379 to 1390. The most important war that occurred during his tenure was the War of the Castilian Succession (1383-1385). This conflict erupted after the death of his father, King Henry II, and involved a power struggle between John I and his half-brother, Ferdinand I of Portugal. The war ended with the Treaty of Salvaterra, which recognized John I as the rightful ruler of Castile and secured his position on the throne.