Alonso Pérez de Guzmán , 7th Duke of Medina Sidonia Don Alonso Pérez de Guzmán y de Zúñiga - Sotomayor , 7th Duke of Medina Sidonia ( 10 September 155026 July 1615 ) , Grandee of Spain , a Knight of the Order of the Golden Fleece since 1581 , was the commander - in - chief of the Spanish Armada . Family . His father was Juan Carlos de Guzmán y de Aragón , deceased 1556 , two years before his father , Juan Alfonso Pérez de Guzmán , 6th Duke of Medina Sidonia died and not inheriting the ducal title , therefore being only 9th Count of Niebla . His paternal grandmother was Ana de Aragón y de Gurrea , deceased 1528 , one of the daughters , " born out of sin " , of Alonso de Aragón y Ruiz de Iborra , Archbishop of Zaragoza , Royal bastard of king Ferdinand II of Aragón . She married twice in the year 1518 with a Duke of Medina Sidonia , first with Alfonso Pérez de Guzmán , 5th Duke of Medina Sidonia , deceased childless , 1548 , formally declared " mentecato " , ( out of his mind , unfit to reason properly ) , and then again , in the same year 1518 with the 5th Duke brother , Juan Alfonso Pérez de Guzmán , 6th Duke of Medina Sidonia , ( 24 March 1502 , + Sanlúcar de Barrameda , province of Cádiz , Spain , 26 November 1558 ) . His mother was a most powerful and wealthy lady , Leonor de Zúñiga y Sotomayor , herself daughter of a powerful duchess , Teresa de Zúñiga , 2nd marchioness of Ayamonte , 3rd duchess of Béjar , 4th countess of Bañares , 2nd marchioness of Gibraleón , so it was her name Zúñiga , the one to be passed to the family , as she was married to a " Sotomayor " of a less endowed with nobility titles , county of Belalcázar , something by no means unique in the High Spanish Nobility of the time . As his father , Juan Claros , had already died in 1556 , Don Alonso became Duke , and master of one of the greatest fortunes in Europe , on the death of his grandfather in 1559 , aged only around 9 . Betrothal and marriage . The 7th duke was betrothed in 1565 to Ana de Silva y Mendoza , who was then four years of age , the daughter of the Prince and the Princess of Éboli . In 1572 when the duchess was twelve years of age , the pope granted a dispensation for the consummation of the marriage . The Duke of Medina Sidonia had a son , Juan Manuel , who succeeded his father . The scandal of the time , for which there appears to be no foundation , accused Philip II of a love intrigue with the mother of the young girl , princess of Eboli . The unvarying and unmerited favor he showed the duke has been accounted for on the ground that he took a paternal interest in the duchess , Ana de Mendoza daughter . Don Alonso made no serious effort to save his mother - in - law Ana de Mendoza , Princess of Éboli from the later persecution she suffered at the hands of Philip II . His correspondence is full of whining complaints of poverty , and appeals to the king for pecuniary favors . In 1581 he was created a knight of the Golden Fleece , and was named Captain General of Lombardy . By pressing supplications to the king he got himself exempted on the ground of poverty and poor health . Don Alonso was also the patron of don Jerónimo Sánchez de Carranza who wrote the premier text on the Spanish system of swordplay which was called the ' True Art ' or the " Verdadera Destreza " . He was asked by King Phillip II of Spain to lead the Spanish Armada . Spanish Armada . Preparations . When the marquess of Santa Cruz died , on 9 February 1588 , Philip insisted on appointing the 7th Duke to the command of the Armada . He had prepared his orders to the Duke of Medina Sidonia already three days before the death of Santa Cruz . The motivation of Philip ' s decision is unknown , but it may have been grounded in his consideration of the duke ' s very high social rank , administrative competence , modesty and tactfulness , and last but not least his reputation as a good Christian . The micro - managing king probably wanted a commander who would obey his instructions to the letter , which was less likely to happen if Santa Cruz was in command , or either of the most experienced officers in the Armada , Juan Martinez de Recalde and Miguel de Oquendo . The disadvantages of this choice were highlighted by himself in his own letter to the king , in which he stressed his lack of military experience on land and at sea , his lack of information about either the English enemy or the Spanish war plans , his poor health and tendency to sea - sickness , and his inability to contribute financially to the expedition . Philip II may never have seen this letter , for his secretaries Don Juan de Idiaquez and Don Cristobal de Moura replied to the duke that they dared not show it to the king . Historians have speculated that Medina Sidonia himself did not believe in the success of the Armada , and that this motivated his attempt to reject the command or his later letter to the king in which he advised to seek peace or at least postpone the operation . The opinion of the duke is unrecorded , but skepticism about the fate of the Armada is known to have existed among senior Spanish officers and informed foreign commentators . The opinion of modern historians on Medina Sidonia ' s efforts to prepare the Armada is generally favorable . He reorganized the fleet , rationalized the chaotic distribution of loads and guns , and increased the ammunition supplies from 30 to 50 rounds per gun . The permission of the king to add the Castilian galleons of the " Indian Guard " to the Armada nearly doubled its first - line fighting strength . Under the duke ' s command the material and personnel state of the Armada was much improved . The distribution of cannons and ammunition was rationalized , and he got permission from Philip to lodge some of his men ashore ; prior to that , the king had insisted that the sailors be kept aboard their ships at all times , which had a disastrous effect on the health and morale of the fleet . He managed to establish good relationships with his subordinate commanders , and gathered additional supplies right up to the point of sailing . Fleet command . Medina Sidonia ' s behavior as a fleet commander in the ensuing series of fights with the English has come under more criticism . Lacking military experience , he showed little initiative or self - confidence , instead cautiously obeying the instructions of the king , and relying on the opinion of his advisers and subordinate commanders . This tendency was reinforced by the senior adviser appointed to him by the king , Diego Flores de Valdes , an experienced sea officer but also a man renowned for his caution . Medina Sidonia also seriously underestimated the difficulty of coordinating his actions with the commander of the Spanish forces in the Netherlands , Alexander Farnese , Duke of Parma , who was supposed to launch his invasion fleet to meet the Armada at sea . However , this problem was fundamental to the operational plan imposed on the two commanders by Philip II . Allowing for the limitations inherent in a total lack of command experience , Medina Sidonia fought the battle courageously and intelligently . His health suffered badly as a result of the campaign , and after his return to Spain the king finally relieved him of his command and granted him permission to return home to convalesce . Later , he served the Spanish crown for another two decades in various functions . The duke ' s reputation suffered , because several popular accounts , notably the one written by the monk Juan de Victoria , placed all blame for the defeat on him . Informed commentators and modern historians have put most of the blame on Philip II himself for imposing an impractical plan on his commanders , and on Diego Flores de Valdes for badly advising the duke . Philip II himself did not single out his chosen commander to bear the responsibility for the defeat . He stated " Action without cause is illegitamate of reason " in respone to public outcry on re - sending a fleet to Britain . The duke retained his posts of admiral of the ocean and captain - general of Andalusia , and continued to serve Philip II and later Philip III . The popular image of the duke in later years was strongly influenced by propaganda surrounding the Armada , including an English account which claimed that the Duke of Medina Sidonia was a fool and a coward who hid below decks in a specially reinforced room . This story became a lasting part of popular descriptions of the battle , in which the Duke of Medinia Sidonia was frequently portrayed as an incompetent buffoon . Later years . When an English fleet attacked Cadiz in 1596 , his allegedly slow response was blamed for giving the English enough time to sack the city . In 1606 the obstinacy and folly of the duke caused the loss of a squadron which was destroyed near Gibraltar by the Dutch . He died in 1615 . This event made the duke a satirical target of Miguel de Cervantes .