The Spanish army of King Philip II, led by the Duke of Alba, decisively defeats the Portuguese forces of António, Prior of Crato, at the battle of Alcantara, who had proclaimed himself king during the Portuguese succession crisis. On August 27, two days after their decisive victory, King Philip captures Lisbon, effectively uniting the crowns of Portugal and Spain.
The following year, on April 16, 1581,the Portuguese Cortes of Tomar, (Parliament), formally recognized King Philip II of Spain as King Philip I of Portugal, resulting in the beginning of the Iberian Union, a personal union of the Spanish and Portuguese crowns that would last for 60 years.
