Fernando Álvarez de Toledo, 3rd Duke of Alba

After Fernando had become the third Duke of Alba in 1532, Charles V sent him to Vienna to help defend the city against an Ottoman invasion army. No battle ensued as the Ottomans, having lost momentum due to time lost during the Siege of Güns, decided not to advance against Vienna and retreated from the field.

During this time, he was accompanied by the soldier-poet Garcilaso de La Vega throughout his travels in Europe. The special access that De La Vega had as a close companion to Alba, coupled with his skilled craft as a writer, allows the historian to delve into the deepest emotions expressed by the Duke of Alba through the poetry of De La Vega. Specifically concerning the ardegous travels while on a war-footing as well as the emotional longing that Alba expressed for his wife.[9]

The Duke's first military command to engage in battle was in the conquest of Tunis. In early June 1535 at Cagliari, he embarked with the military force commanded by the Marquess of Vasto. On 14 July, the fortress of La Goleta was seized, and a week later the army took the city of Tunis which was defended by Hayreddin Barbarossa. Thus Spain regained control over the western Mediterranean Sea.

In 1542, he led the Spanish troops against the French Army, ending the siege of Perpignan. The siege was a decisive victory for Alba and one of the worst defeats of Francis I during the French offensive of 1542.

In 1547, Charles I, in his capacity as Charles V, Holy Roman Emperor engaged with the Protestant forces in the Schmalkaldic War. The Duke of Alba was in charge of Tercios, the elite Spanish ground troops during the Battle of Mühlberg on the banks of the river Elbe. A flanking attack by Alba's Tercios was largely responsible for the imperial army's decisive victory against the Elector of Saxony.

The Duke of Alba in 1549 by Anthonis Mor

In later years, the focus of conflict between France and Spain had moved to the Italian peninsula. Alba was sent to Italy as commander in chief of the Spanish-Habsburg army in Italy, and became governor of Milan in 1555, and viceroy of Naples in 1556.

The newly appointed Pope Paul IV, an enemy of the Habsburgs, prompted King Henry II of France to expel the Spanish from Italy. Papal troops joined the French for this aim. In July 1556 the Pope declared Philip II was removed from the title King of Naples. Alba did not hesitate[10] and marched on Rome at the head of 12,000 Spanish soldiers. He financed the campaign, in part, by obtaining a loan of 430,000 ducats from Bona Sforza, dowager Queen of Poland; the loan became known as Neapolitan sums and was never repaid.[11] The Pope called for a truce, giving time for a French army commanded by Francis, Duke of Guise to march on Naples. The Spanish intercepted the French and defeated them in the Battle of San Quentin. Without French support, the papal troops were overwhelmed by the Spanish and the Duke of Alba entered Rome in September 1557. The pope had to sue for peace.[12]

In April 1559, Alba was one of the signatories of the Treaty of Cateau-Cambrésis which ended their war with France and released Spanish resources for maximising its economic exploitation of New Spain. The Italian peninsula entered a prolonged period of peace, sealed by marriage between the twice widowed Philip II and Isabel de Valois, daughter of Henry II of France. During the royal wedding, which was held in Paris, Alba acted as proxy for Philip.[13]

Engraving of the statue of Fernando Álvarez de Toledo in Antwerp by Jacques Jonghelinck. From Nederlantsche Oorloghen by Pieter Bor

Head of a bronze medal with the effigy and the cuirass of the Grand Alba bearing the Golden Fleece in commemoration of his triumphs in 1571 with the Latin legend «FERDIN[andus] • TOLET[anus] • ALBÆ • DUX • BELG • PRÆF[ectus]», which means, in English, "Fernando de Toledo Duke of Alba Governor of the Netherlands"

Back of the same medal with the Latin inscription «DEO et REGI VITÆ VSVS», which means, in English, "God and King are purposes of life"

Fernando Álvarez de Toledo by Willem Key (1568)

From August to October 1566, the "Iconoclasm" (Dutch: Beeldenstorm) took place in the Netherlands, during which Calvinist mobs attacked and destroyed numerous Catholic monasteries and churches, ransacking tombs and destroying statues. To tackle both civil and religious rebels, King Philip II sent the 3rd Duke of Alba to Brussels on 22 August 1567, at the head of a powerful army. On arrival, Alba replaced Margaret of Parma, the sister of the Spanish king, as head of the civil jurisdiction. He decided that the local nobility was in open rebellion against the king and supported the new Protestant teachings, heresy in his view.

A few days later, on 5 September 1567, Alba established the "Council of Troubles", popularly known in the Netherlands as the "Court of Blood," to prosecute those responsible for the riots of 1566, especially those who were deemed heretics. Alba also targeted the local Catholic nobility, who favoured dialogue and opposed outside intervention. Two of the three heads of the Flemish nobility, the Count of Egmont, a Catholic General for Philip II, who had led the cavalry that defeated the French at the Battle of San Quentin, and Philip de Montmorency, Count of Horn, were arrested. The court sentenced both counts to death. The Major of Antwerp, Anthony van Stralen, Lord of Merksem and Jan van Casembroot were other famous victims of the bloody repression, along with a large group of other "heretics". The condemned persons were executed on 5 June 1568 in the Town Hall Square in Brussels. Alba had little confidence in Flemish justice, which he perceived as sympathetic to the defendants, and witnessed the executions in person.

The maintenance of the troops in Flanders entailed substantial economic costs. The Duke decided to impose new taxes on the population. Some cities, including Utrecht, refused to pay the "tithe" and declared a rebellion, which quickly spread throughout the Netherlands. William the Silent, the prince of Orange, enlisted the help of the French Huguenots; and started to actively support the rebellion. William and the Huguenots took many Dutch cities. The Spanish troops advanced under banners with the Latin legend Pro lege, rege, et grege, which in English means For the law, the king, and the people [literally, the flock]. In 1572 the Spanish army carried out the Spanish Fury at Mechelen, retaking and sacking the city after the rebel garrison had left. From there, Spain retook Zutphen and Naarden. The Spanish Siege of Haarlem, characterized by brutality and savagery on both sides, culminated in the surrender of the city and the execution of all the garrison, estimated at 2,000 men. The subsequent Siege of Alkmaar was unsuccessful however; and was the first defeat in a full scale engagement for the Spanish troops during the Dutch revolt. The prolonged military campaigns and the harsh repression of the rebel citizenry earned the 3rd Duke of Alba the nickname "The Iron Duke" in the Netherlands,[14][15][16] and he became an important element of the anti-Spanish Black Legend.[17] His reputation was used for propaganda purposes by rebel statesman Philips of Marnix, Lord of Saint-Aldegonde to further strengthen anti-Spanish sentiments in the Netherlands.

In spite of continuous military action, the political situation in the Netherlands had not turned in favour of the Spanish crown. After five years of repression, more than 5,000 executions[18] and numerous complaints to the Spanish court, Philip II decided to change policy and relieve the Duke of Alba. The monarch sent Luis de Requesens to replace Alba. De Requesens tried to appease the situation by giving concessions to the rebels. Alba returned to Spain in 1573.

Nevertheless, the Duke still had influence in the Royal Council. Alba belonged to the conservative Spanish faction called Albistas or imperialists. This faction included the Inquisitor General Fernando de Valdés y Salas, the House of Pimentel, the Duke de Alburquerque and other members of the House of Álvarez de Toledo. The Albistas advised the king to take a firm stand in the Netherlands. The Albistas' hardline position was hotly contested by the liberal Ebolistas or humanists, led by Ruy Gómez de Silva, prince of Éboli and his secretary Francisco de Eraso. After the death of the prince of Éboli in 1573, the royal secretary Antonio Pérez went on to lead the liberal faction and began his association with Ana de Mendoza de la Cerda, Princess of Éboli. Against the Albistas' urging, King Philip II himself publicly acknowledged that "it is not possible to carry Flanders forward by way of war."[19] Political concessions by Luis de Requesens failed to end the rebellion in the Netherlands and hostilities soon resumed. These failures of the Ebolistas to end the Dutch revolt raised the distrust of the king, and Philip II again granted the Duke of Alba an important position in court.

After the death of King Sebastian of Portugal, who had no heirs, in the Battle of Alcácer Quibir in 1578, the crown fell to his great uncle Cardinal Henry I of Portugal.[20] The death of the latter, without any appointed heirs, led to the Portuguese succession crisis of 1580.[21]

One of the claimants to the throne, António, Prior of Crato, a bastard son of Infante Louis, Duke of Beja and only grandson through the male line of king Manuel I of Portugal, was proclaimed King in June 1580.[22][23]

Philip II, through his mother Isabella of Portugal also a grandson of Manuel I, did not recognize Antonio as king of Portugal. The king appointed Fernando, Duke of Alba, as captain general of his army.[24] The duke was 73 years old and ill at the time.[25] Fernando mustered his forces, estimated at 20,000 men,[26] in Badajoz, and in June 1580 crossed the Spanish-Portuguese border and moved to Lisbon. In late August he defeated a Portuguese army at the Battle of Alcântara and entered Lisbon. This cleared the way for Philip II who became Philip I of Portugal, and created a dynastic union spanning all of Iberia under the Spanish crown.[27]

King Philip II rewarded Fernando with the titles of 1st Viceroy of Portugal and Constable of Portugal on July 18, 1580. With these titles Fernando represented the Spanish monarch in Portugal and was second in hierarchy only after the king in Portugal. Fernando held both titles until his death in 1582.[28]