The Portuguese Crisis of 1383-1385 was a significant conflict in Portugal that arose after the death of King Fernando I. Without a clear heir, the throne was contested, leading to a power struggle between the supporters of Fernando's daughter, Beatrice, and those favoring John I of Aviz. This crisis threatened the stability of the Portuguese crown and the nation's independence. The conflict escalated into a civil war, culminating in the decisive Battle of Aljubarrota in 1385. The forces of John I emerged victorious, securing his position as king and establishing the Aviz dynasty. This victory not only solidified Portugal's independence but also marked the beginning of a new era in Portuguese history.