The Spanish Invasion of Portugal and the …

Years: 1580 - 1580
June

The Spanish Invasion of Portugal and the Fall of Dom António (1580)

In June 1580, King Philip II of Spain, one of seven claimants to the Portuguese throne, launched a full-scale military invasion of Portugal. His forces, numbering around 40,000 men—including 20,000 Spanish regulars and 20,000 mercenaries—were led by the experienced Fernando Álvarez de Toledo, Duke of Alba.

With Portugal's army decimated at the Battle of Ksar El Kebir (1578) and noble support turning toward Philip II, Dom António, Prior of Crato, was left to defend the country with an irregular army of peasants, townspeople, and freed enslaved Africans.


Background: The Devastation of Portugal’s Army at Ksar El Kebir (1578)

  • The disastrous Battle of Alcácer Quibir (Ksar El Kebir) in 1578 had resulted in:
    • The death of King Sebastian I and much of Portugal’s nobility.
    • The capture of thousands of Portuguese soldiers, most of whom never returned from Moroccan captivity.
  • This left Portugal militarily crippled, making it vulnerable to Spanish aggression.

Dom António’s Struggle for the Throne

  • With Philip II claiming the Portuguese crown, Dom António, Prior of Crato, attempted to resist Spanish rule.
  • However, the remnants of Portugal’s high clergy and nobility sided with Philip, fearing that António, as an illegitimate claimant, could not ensure stability.
  • Unable to recruit professional soldiers, António was forced to assemble a makeshift army, consisting of:
    • Local peasants and townspeople, most of whom were untrained.
    • 3,000 enslaved Africans, who fought in exchange for their freedom.

Conclusion: The Weakness of Dom António’s Forces

Despite his desperate resistance, Dom António’s irregular forces stood little chance against Philip II’s well-equipped and battle-hardened Spanish army. The battle for Portugal’s independence would soon culminate in the decisive Spanish victory at the Battle of Alcântara (August 25, 1580), marking the beginning of sixty years of Spanish rule over Portugal (1580–1640) under the Iberian Union.

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