Mariana of Austria

First regency: 1665–1677

Charles was only three years old when Philip died on 17 September 1665, and Mariana was appointed regent, advised by a Regency Council, until he became a legal adult at the age of 14. She adopted the valido ^[b] system established by Philip in 1620, the first being Juan Everardo Nithard, an Austrian Jesuit and her personal confessor; as Philip's will excluded foreigners from the Regency Council, he had to be naturalised, causing immediate resentment.^[7] Other informal advisors included Gaspar de Bracamonte, 3rd Count of Peñaranda and Mariana Engracia Álvarez de Toledo Portugal y Alfonso-Pimentel.^[8]

Charles' poor health and lack of an heir meant his reign was often dominated by a power struggle between Mariana's Austrian faction, and a pro-French lobby initially led by his illegitimate half-brother, John of Austria the Younger. Spain was also divided into the Crowns of Castile and Aragon, whose very different political cultures made it almost impossible to enact reforms or increase taxes. As a result, government finances were in perpetual crisis, the Crown declaring bankruptcy in 1647, 1652, 1661 and 1666.^[9]

Spain was exhausted by almost a century of continuous war, while the second half of the 17th century coincided with a period of extreme cold weather known as the Little Ice Age. Between 1692 and 1699, crops failed across Europe and an estimated 5–10% of the population starved to death.^[10] The new government inherited other problems, the long-running Portuguese Restoration War being the most urgent. This was made worse in May 1667 when France once again invaded the Spanish Netherlands, and occupied the Spanish province of Franche-Comté.^[11] The Treaty of Aix-la-Chapelle (1668) ended the war with France, while the Treaty of Lisbon (1668) restored Portugal's independence.^[12]

Peace ended the drain on Spanish resources, while France returned most of the territories over-run in the War of Devolution. They represented a significant diplomatic achievement, but many Spanish military officers considered the terms humiliating. Joseph Malladas, an Aragonese captain, was executed in June 1668 for plotting to murder Nithard, reputedly on John's behalf.^[13] In February 1669, Nithard was succeeded as valido by Aytona, who died in 1670 and replaced in turn by Valenzuela, a member of her household since 1661.^[14] An outsider from the lower ranks of Spanish nobility, Valenzuela depended entirely on Mariana for his position.^[15]

In 1672, Spain was dragged into the Franco-Dutch War; Valenzuela was dismissed when Charles came of age in 1675, but Spanish policy continued to be undermined by the struggle for power. Mariana reinstated the regency in 1677 on the grounds of Charles's ill-health and Valenzuela was restored, before John finally gained control in 1677.

Second regency: 1679–1696

John died in September 1679 and Mariana became regent once again; one of his final acts was arranging the marriage of Charles to 17-year-old Marie Louise of Orléans, which took place in November 1679.^[16] She died in February 1689, without producing an heir; as with many deaths of the period, limited medical knowledge led to allegations she was poisoned. Modern assessments of her symptoms conclude it was almost certainly appendicitis, possibly from the treatments undertaken to improve fertility.^[17]

Her replacement was Maria Anna of Neuburg, one of 12 children whose family reputation for fertility made them popular choices for royal marriages. Of her sisters, Maria Sophia married Peter II of Portugal, while Eleonore was the third wife of Leopold I, Holy Roman Emperor. Maria Anna was aunt to future emperors Joseph I and Charles VI, making her an ideal choice for the Austrian faction.^[18] However, Charles was by now almost certainly impotent, his autopsy later revealing he had only one atrophied testicle.^[19]

As his health declined, internal struggles over the succession became increasingly bitter, leadership of the pro-French faction passing to Fernández de Portocarrero, Archbishop of Toledo. In 1690, Spain joined the Grand Alliance in the Nine Years' War with France. It declared bankruptcy again in 1692 and by 1696, France occupied most of Catalonia; Mariana retained power with the support of German auxiliaries under Maria Anna's brother Charles Philip, many of whom were expelled after Mariana's death.^[20] She died on 16 May 1696 at the Uceda Palace in Madrid, at the age of sixty-one, probably from breast cancer.^[21]