Fernando Alvarez of Toledo and Pimentel ( Piedrahita , October 29, 1507 - Lisbon , 11 December 1582 ), called the Grand Duke of Alba , was a noble , military, Spanish diplomat , III Duke of Alba de Tormes and Huéscar , Marquis of Coria IV , III Count of Salvatierra de Tormes , II and VIII Mr. Piedrahita Valdecorneja , Grandee of Spain and Illustrious knight Order of the Golden Fleece He was the most trusted man and obedience of the kings of Spain Carlos I and his successor Philip II , both chief steward and member of its Council of State and War . Government took over the Duchy of Milan (1555-1556) , the Kingdom of Naples (1556-1558) , of the Netherlands (1567-1573) and the Kingdom of Portugal (1580 -1582 ) . Represented Philip II in his betrothal to Elizabeth of Valois , daughter of Henry II of France and Anne of Austria , daughter of Holy Roman Emperor Maximilian II . Considered by historians as the best general of his time and one of the best ever , especially distinguished himself in the day Tunisia , and in battles as Mühlberg , Jemmingen and Alcantara . Immortalized his memory trying to appease the sedition of the Netherlands , where he performed with great rigor punishing the rebels , instituting the famous Court of Troubles and repeatedly defeating the troops of William of Orange and Louis of Nassau in the early stages of the Eighty Years war . He capped his career as an old man with the succession crisis in Portugal in 1580, conquering that kingdom to Philip II . Because of his military genius Spain achieved the unification of all the kingdoms of the Iberian Peninsula and the consequent expansion of the overseas territories .