Which 1385 battle secured Portugal’s independence from a Castilian invasion?

The 1385 Battle of Aljubarrota secured Portugal’s independence from a Castilian invasion.

The battle was fought on 14 August 1385 near Aljubarrota in central Portugal. Portuguese forces under King John I and the constable Nuno Álvares Pereira defeated a substantially larger Castilian army. English troops and longbowmen supported the Portuguese side, reflecting the alliance between Portugal and England.

Portuguese commanders used defensive positions, obstacles, and the terrain to restrict the movement of Castilian cavalry. The victory ended the immediate Castilian attempt to place John of Castile on the Portuguese throne and strengthened the Avis dynasty. John I of Portugal later married Philippa of Lancaster, reinforcing the Anglo-Portuguese relationship.

Aljubarrota is sometimes confused with the 1387 Battle of Valverde, another Portuguese victory associated with Nuno Álvares Pereira. They were separate battles in the same broader political struggle.