The bourgeoisie of Lisbon, enriched by commerce, decided to support Joćo and donated substantial sums for war expenses. Money also arrived from the bourgeoisie in Porto, Coimbra, and Évora. The majority of the nobility, among whom national sentiment was not well developed and feudal customs based on oathĶĶĶĶs of vassalage were still obeyed, took the side of Juan of Castile, which gave him the support of fifty castles. A few nobles, however, including Įlvaro Pais, Joćo Afonso, and Nun'Įlvares Pereira, were more attuned to national sentiment and sided with Joćo.

In March 1384, Juan marched on Lisbon, which he besieged by land and sea. In April, in the Alentejo, Nun'Įlvares Pereira defeated the Castilians at the Battle of Atoleiros, a victory that resulted from the new military tactic of forming defensive squares from dismounted cavalry because the Portuguese had far fewer troops than the enemy. The siege of Lisbon was broken after seven months by an outbreak of the plague in the Castilian camp, and Juan retreated to Seville to prepare another invasion the following year.

The retreat of the Castilians gave Joćo an opportunity to legitimate his claim to the throne. In March 1385, a cortes was summoned to resolve the succession. Joćo's case was argued by Joćo das Regras, who attacked the claims of the various pretenders to the throne. On April 6, the opposition ended and Joćo was proclaimed king as Joćo I (r. 1385-1433). The new king named Nun'Įlvares Pereira constable of Portugal. At the same time, a contingent of English longbowmen began to arrive. Nun'Įlvares Pereira marched north in order to obtain the submission of Braga, Guimarćes, and other places loyal to Juan, who responded by sending an army to attack Viseu. The Portuguese routed this Castilian force at Rancoso using the same new military tactic that brought them victory at Atoleiros. Juan, nonetheless, was still intent on besieging Lisbon and led his army southward. Joćo I and Nun'Įlvares Pereira decided to engage Juan's army before it arrived in the capital. The two armies met on the plain of Aljubarrota about sixty kilometers north of Lisbon on August 14, 1385. Using the same tactic of defensive squares of dismounted cavalry that had brought them success in previous battles, a force of 7,000 Portuguese annihilated and scattered a Castilian army of 32,000 in little more than thirty minutes of combat. Although additional battles were fought and final peace was not made with Castile until October 1411, the Battle of Aljubarrota secured the independence of Portugal for almost two centuries.

Data as of January 1993