Portugal Wins Aljubarrota: Independence from Castile

Six thousand Portuguese troops destroyed a Castilian army three times their size on the fields of Aljubarrota on August 14, 1385, securing Portuguese independence for the next two centuries and launching a dynasty that would build a global maritime empire. King Joao I, who had been Master of the Order of Aviz barely a year earlier, gambled everything on a single afternoon and won. The battle was the climax of the Portuguese succession crisis that had convulsed the Iberian Peninsula since 1383. When King Fernando I died without a male heir, his daughter Beatriz's marriage to King Juan I of Castile gave the Castilian monarch a claim to the Portuguese throne. Much of the Portuguese nobility supported this union, but the merchant class, the lesser nobility, and the common people of Lisbon rallied behind Joao, Fernando's illegitimate half-brother. Joao was proclaimed king by the Cortes at Coimbra in April 1385, and Juan I invaded with the largest army assembled in Iberia in a generation. Joao's constable, Nuno Alvares Pereira, chose the battlefield carefully. He positioned the Portuguese force on a ridge near the village of Aljubarrota, with narrow approaches flanked by streams and rough terrain that neutralized the Castilian advantage in numbers. The Portuguese deployed dismounted men-at-arms supported by English longbowmen, a tactic borrowed from the English victories at Crecy and Poitiers. When the Castilian cavalry charged uphill, they were funneled into killing zones and cut apart. The battle lasted less than an hour. Juan I fled the field, abandoning his camp, treasury, and royal chapel. Castilian casualties ran into the thousands, including much of the kingdom's high nobility. The Treaty of Windsor, signed the following year, established an Anglo-Portuguese alliance that remains the oldest diplomatic alliance still in force. Joao I founded the Aviz dynasty, and his sons, particularly Prince Henry the Navigator, would launch the Portuguese Age of Discovery that reshaped the world.