Alonso Pérez de Guzmán y Sotomayor, the 7th Duke of Medina Sidonia (10 September 1550 - 26 July 1615), often called El Bueno ("The Good One"), was one of the highest-ranked noblemen in HapsburgSpain, equally notorious for his fabulous wealth and military ineptitude.
In a movement that has puzzled historians ever since, King Philip II named Medina Sidonia as the successor of Admiral Álvaro de Bazán as the supreme commander of Spanish Navy, following Bazán's untimely death on 9 February 1588. As such, Medina Sidonia was to commander the Spanish Armada that had been assembled to invade England and overthrow Queen Elizabeth. Medina Sidonia attempted to refuse, arguing that he had no naval experience and was prone to seasicknes, but the monarch stood firm in his decision. Long time naval officer Diego Flores de Valdés was appointed chief advisor of Medina Sidonia, and upon their return, took most of the blame for the Armada's ill-chosen defensive strategy and defeat. Meanwhile, Medina Sidonia retired to his lands unscathed.
Medina Sidonia continued to serve the Spanish government in the same capacity for the following 20 years, even after his timidness and slowness to respond allowed an Anglo-Dutch fleet to sack Cádiz in 1596.