Documents dated 1588 have surfaced, detailing the formal appointment of Duke Dom Alonso Pérez de Guzmán as the leader of the expedition following the death of the Marquis of Santa Cruz. These documents also include detailed military instructions pertaining to the voyage, coordination with the army of the Duke of Parma in Flanders, and potential alternative actions in case of setbacks.
The Spanish Armada was a fleet dispatched by Philip II during the Anglo-Spanish War (1585-1604) meant to invade England and depose Elizabeth I, restore Catholicism, contain English support for the independence of the Netherlands, then under Spanish rule, and curb pirate attacks on Spanish routes and colonies.
The documents also contained a secret instruction outlining the capture of the Isle of Wight and the capture of the pretender to the Portuguese throne, Dom António.
Dom António, Prior of Crato, who lived from 1531 to 1595, was the grandson of King Manuel I and laid claim to the throne of Portugal in 1580 following the disappearance of King Sebastian at the Battle of Alcácer Quibir in 1578.
Furthermore, there was an order signed by Medina Sidonia himself aboard the galleon San Martín, providing guidance on naval combat, security, and discipline on board.
The letters, previously held in private collections, offer valuable insights into the preparations for one of the largest naval operations of the 16th century, which ultimately resulted in a significant defeat for Spain due to a combination of military, strategic, meteorological, and logistical factors.
