The auction will take place online from June 26 to July 10, organized by Sotheby’s in London, with an estimated maximum value of 300,000 pounds (350,000 euros).
The documents, dated 1588, include the formal appointment of the duke, Dom Alonso Pérez de Guzmán, as the leader of the expedition following the death of the Marquis of Santa Cruz, along with detailed military instructions about the voyage, coordination with the Duke of Parma’s army in Flanders, and possible alternative actions in case of setbacks.
The Spanish Armada was a fleet sent by Philip II during the Anglo-Spanish War (1585-1604) to invade England, overthrow Elizabeth I, restore Catholicism, suppress English support for the independence of the Netherlands—then under Spanish rule—and curb pirate attacks on Spanish routes and colonies.
The documents also include a secret instruction contemplating the capture of the Isle of Wight and the capture of the Portuguese throne pretender, Dom António.
Dom António, Prior of Crato, who lived from 1531 to 1595, was a grandson of King Manuel I and presented himself as a candidate for the Portuguese throne in 1580, after the disappearance of King Sebastian at the battle of Alcácer Quibir in 1578.
They also contain an order signed by Medina Sidonia himself aboard the galleon San Martín, with guidelines on naval combat, security, and discipline aboard.
The letters, previously held in private hands, offer valuable information about the preparations for one of the largest naval operations of the 16th century, which culminated in a significant defeat for Spain due to a combination of military, strategic, meteorological, and logistical factors.
