Ferdinand I was born in Alcala de Henares on 10 March 1503, to the Infanta Joanna of Castile and to Habsburg Archduke Philip the “Handsome,” Duke of Burgundy and future King of Castile, who was heir to Emperor Maximilian I. His brother Charles V entrusted Ferdinand with the government of the Austrian hereditary lands, roughly modern-day Austria and Slovenia. Ferdinand also served as his brother’s deputy in the Holy Roman Empire during his brother’s many absences and in 1531 was elected King of Germany as a reward for his loyalty to his brother the Holy Roman Emperor Charles V, making him heir in the Empire. Charles abdicated in 1556 and Ferdinand succeeded him, assuming the title of Emperor elect in 1558.

In 1526, Ferdinand was elected King of Bohemia and Hungary to replace his brother-in-law Louis II, who had been defeated by the Turkish under Suleiman the Magnificent. The worst and most dangerous moment of Ferdinand’s career took place in 1529 when he sought refuge in Bohemia from a massive attack on his capital by a Muslim army under Suleiman, the Ottoman Sultan, at the Siege of Vienna. The attack was repulsed and the capital Vienna saved. Another Ottoman attack on Vienna was repelled in 1533. In that year Ferdinand signed a peace treaty with the Ottoman Empire, splitting the Kingdom of Hungary into a Habsburg sector in the west and an eastern domain under John Zapolya, who ruled a vassal state of the Ottoman Empire.

Maximilian I was born in 1459, in Wiener Neustadt, to Emperor Frederick III and Eleanor of Portugal. In 1477, he married the heiress of Burgundy, Mary, the only daughter of Charles the Bold, Duke of Burgundy. Through this marriage, Maximilian obtained the Burgundian Netherlands and the Free County of Burgundy, although he lost the Duchy of Burgundy to France upon the death of his wife. In 1491, he bought Tyrol and Further Austria from his cousin Sigismund, the last member of the Elder Tyrolean Line of the House of Habsburg.

On February 16, 1486, Maximilian was elected king of the Romans in Frankfurt am Main at his father’s initiative and crowned on April 9, 1486 in Aachen, and in 1508 with Pope Julius II’s assent, he took the title of Elected Roman Emperor. In 1494 Maximilian married Bianca Maria Sforza, a daughter of the Duke of Milan, seeking to expand his power in parts of Italy. This brought French intervention in Italy, inaugurating the prolonged Italian Wars.

Don Fernando Alvarez de Toledo y Pimentel, 3rd Duke of Alba was a Spanish governor and general of the Spanish Netherlands between 1567 and 1573, nicknamed "the Iron Duke" by Protestants of the Low Countries because of his harsh rule. He became part of Dutch and English folklore, forming a new and central component of the Black Legend. The Duke of Alba was a stickler for discipline and a master of logistics, contributing significantly to the defeat of the German Protestants at the battle of Mühlberg in 1547.

Fernando Alvarez de Toledo was born in 1507, in Spain. Alba’s grandfather, Fadrique Alvarez de Toledo, educated him in military science and politics. While he was still a young officer,  he fought with distinction at the Battle of Pavia in 1525.  The Duke of Alba was selected for a military command by Charles V, and took part in the siege of Tunis in 1535, and successfully defended Perpignan against the dauphin of France. He was present at the Battle of Mühlberg in 1547, and the victory gained there over the Prince-Elector Johann Friederich of Saxony was due mainly to his exertions.

Also known as the War of Cyprus, the Fifth Ottoman–Venetian War was fought between the Ottoman Empire and the Republic of Venice from 1570 to 1573. The latter was aided by the Holy League, a coalition of Christian states formed under the auspices of the Pope and including Spain, with Naples and Sicily, the Republic of Genoa, the Duchy of Savoy, the Knights Hospitaller, the Grand Duchy of Tuscany and other Italian states.

The war broke out when the Ottomans under Sultan Selim II invaded the Venetian-held island of Cyprus. The capital Nicosia and several other towns fell quickly to the superior Ottoman army, leaving only Famagusta in Venetian hands. As Christian reinforcements were delayed, Famagusta could not hold out and eventually fell in August 1571 after a siege of 11 months. Two months later, at the Battle of Lepanto, the united Christian fleet destroyed the Ottoman fleet, but was unable to take advantage of this victory. The Ottomans quickly rebuilt their naval forces, and Venice was forced to negotiate a separate peace, ceding Cyprus to the Ottomans and paying a tribute of 300,000 ducats.

When Charles V abdicated his Spanish crowns in 1556, he summoned Don Luis de Quijada to return as majordomo. In the summer of 1558 Quijada brought Magdalena and Jeromín to Yuste, where Charles saw his son on several occasions before his death. By this time Jeromin was eleven. Although he did not acknowledge him as his son at the time, Charles had made provision in his will for Jeromín and expressed hope that he would enter the clergy and pursue an ecclesiastical career. Charles’ legitimate son and heir, Philip II of Spain, returned from Brussels in 1559, aware of his father’s will. In Valladolid, he summoned Quijada to bring Jeromín to a hunt. As Philip appeared, Quijada told Jeromín to dismount and make proper obeisance to his king. After Jeromín did so, Philip asked him if he knew who his father was. But the boy did not know, and Philip embraced him and explained that they had the same father and were brothers. He would ever after address him as “my very dear and beloved brother”. And Philip renamed him Juan, after a brother who died in infancy.

As John was not considered a Spanish royal prince, he was not to be addressed as "highness", a form reserved for royals and sovereign princes, for Philip was strict with protocol and did not accord him royal status. In formal style John was “your excellency,” the form for a Spanish grandee, and known as Señor Don Juan de Austria, who was not to live in royal palaces or quarters, but to maintain a separate household, with Luis and Magdalena Quijada now heading his service. Philip did allow Don John the incomes allocated to him by Charles so that he might maintain the status proper to the son of an emperor and brother of a king. In public ceremonies, Don John stood, walked or rode behind the royal family, but ahead of the grandees.

Hoping that Don John would take up an ecclesiastical career, sent him to the University of Alcala de Henares in the company of Don Carlos and Alexander Farnese, Prince of Parma and son of Charles V’s. But there he only learned womanizing and soon excelled at it in his own right. In time, he would acknowledge two illegitimate daughters, one in Spain, the other in Naples. Athough Don John did not fulfill his father’s and brother’s hopes that he would enter the clergy, he pursued a military career, which was more to his liking.

In 1565, the eighteen-year-old Don John left the court for Barcelona to join the armada for the relief of Malta, besieged by the Ottoman Turks. In 1566 he was awarded the 245th Knight of the Order of the Golden Fleece. In 1568, when Don John turned twenty-one, Philip appointed him Captain General of the Sea, commander of Spain’s Mediterranean galley fleet. Don John embarked with Spain’s galley fleet that spring, assisted by veterans such as Don Álvaro de Bazán, the later Marquis of Santa Cruz. He patrolled Spain’s coast and chased Barbary corsairs, his first foray into combat.

When news reached John of Austria of the revolt of the Moors in Granada, he volunteered to serve in any capacity. As the revolt spread with the foreign aid from the Barbary and the Turks, Philip appointed Don John commander-in-chief in April 1569, with Quijada his chief adviser. In Granada Don John built his forces with care, learning about logistics and drill and dealing with jealous local authorities. In December Don John unexpectedly took the field with a large and well-supplied army. First clearing rebels from near Granada, he then marched east through Guadix, where veteran troops from Italy joined him, bringing his numbers to 12,000 men. In late January he assaulted the Islamic stronghold of Galera. Fighting was long and hard and causalties heavy. When Galera fell, Don Juan had it leveled and salt ploughed into its soil, for the Muslim Moors were deemed unreliable and treacherous as they did not abide by earlier peace treaties and truce, attacking Christian populations unexpectedly and vicously.

In August 1571, Cyprus had fallen in the hands of the Turks during the Ottoman-Venetian War. This event led the Christian powers of the Mediterranean to fear for the safety of the Adriatic. A league between Spain and Venice was created by the efforts of Pope Pius V to resist the Turkish advance to the west, and Don John was named admiral in chief of the combined fleets. At the head of 208 galleys, 6 galleasses and a number of smaller craft, Don John encountered the Turkish fleet at Lepanto on October 7, 1571, and gained a complete victory. Only forty Turkish vessels managed to escape, and it was computed that 35,000 of their men were slain or captured while 15,000 Christian galley slaves were released.

In 1573, Don John put his energy into the recovery of Tunis, which he achieved that fall. Against advice from Madrid to raze Tunis and destroy its harbor and the great fortress of La Goletta, erected by Charles V after the conquest of Tunis in 1535, Don John chose to keep La Goletta, which had held out in 1570, and build a new fortress inside Tunis to dominate the city. He and the Marquis of Santa Cruz planned next to take Algiers, while critics, including Granvelle, hinted that Don John dreamed of becoming King of Tunis.

In 1574, a huge Turkish armada under Uluj Ali struck Tunis and within weeks, both La Goletta and the new city citadel were lost. Don John had hurried to Palermo and assembled all available forces, but it was too little and too late. He came to feel abandoned and though Philip had enhanced his authority over the viceroys of Naples and Sicily, he returned to Madrid at the beginning of 1575 to confer in person with Philip and the Council of War. He claimed to be unaware that orders had been sent that he remain in Italy. Wars on two fronts, the Low Countries and the Mediterranean, had overtaxed his finances, and he suspended payments on debts prior to their renegotiation. With Santa Cruz in Naples, Don John could undertake little but occasional punitive strikes against Islamic Tunisians with his reduced fleet.

In 1576, John of Austria received orders to proceed directly to the Low Countries as Governor General in succession to Luis de Requesens. Grievances in the Low Countries were many, but at the heart of the revolt was religion, militant Calvinism on the rebel side, Roman Catholicism on Philip’s. As the administration of Luis de Requesens had not been successful, the revolt headed by the Prince of Orange spread, and at the time of Don John’s nomination the Pacification of Ghent appeared to have united the whole of the seventeen provinces of the Netherlands in determined opposition to Spanish rule and the policy of Philip II. The Pacification of Ghent, which was really a treaty between Holland and Zeeland and the other provinces for the defense of their common interests against Spain, had been followed by an agreement between the southern provinces, known as the Union of Brussels, which aimed at the expulsion of the Spanish soldiery and officials from the Netherlands.

Confronted by the refusal of the states general to accept him as governor unless he assented to the conditions of the Pacification of Ghent, Don John, after some months of fruitless negotiations, saw himself compelled to give way. At Huey on the February 12, 1577 he signed a treaty, known as the Perpetual Edict, in which he complied with these terms. On the May 1 he made his entry into Brussels, but he found himself governor-general only in name, and the Prince of Orange master of the situation. However, in July 1577, Don John suddenly went over to Namur and withdrew his concessions while William of Orange took up his residence at Brussels, and gave his support to the archduke Matthias, afterwards emperor, whom the states-general accepted as their sovereign.