The Battle of Alcântara was a crucial confrontation during the War of the Portuguese Succession, a conflict that arose over the legitimacy of claims to the Portuguese throne following King Henry's death. Philip II of Spain laid claim to the Portuguese crown based on his maternal lineage, which was contested by various factions in Portugal. The battle occurred near the town of Alcântara, where Spanish forces faced off against Portuguese loyalists. Leadership from both sides was significant, with Philip II supported by a well-prepared and armed force. The tactical proficiency of the Spanish army, along with their superior numbers, played a central role in the outcome of the battle.

Following a series of engagements, the Spanish emerged victorious, which was pivotal in solidifying Philip II's claim to Portugal. The aftermath resulted in the establishment of the Iberian Union, effectively merging the crowns of Spain and Portugal under a single monarch for sixty years. This union had substantial implications for the administration and colonial ambitions of both kingdoms, as it allowed for coordinated efforts in the New World and Asia, enhancing Spanish power but also leading to resentment among Portuguese nationalists.

The Battle of Alcântara and its outcome contributed to the complexities of Iberian politics in the late 16th century, provoking internal divisions and setting the stage for future conflicts and the eventual fall of the union. The legacy of this battle continued to resonate for centuries, illustrating the impact of dynastic struggles on national sovereignty and colonial power dynamics.