Margaret Theresa of Spain was born on July 12, 1651, in the Royal Alcazar Palace in Madrid. Her father was King Philip IV, who had ruled Spain since 1621 after taking the throne at just 15 years old. He was known as "Rey Planeta," or the Planet King, because Spain's empire stretched around the world.
Her mother was Mariana, or Maria Anna, of Austria, a daughter of Ferdinand III, Holy Roman Emperor. Both of her parents belonged to the House of Habsburg, a dynasty that rose from the borderlands of Switzerland and Austria in medieval times. Through strategic marriages rather than constant warfare, the Habsburgs came to control vast territories across Europe.
By the late 15th century, the family had inherited the Spanish throne and become one of Europe's most powerful forces. But the Habsburgs were also infamous for a dangerous obsession with inbreeding. Generation after generation, they married within their own bloodline, sealing alliances at the cost of their own health.
Margaret Theresa's parents were far closer than distant relatives. Her father came from the Spanish branch of the family and her mother from the Austrian side, but their connection ran much deeper. In a shocking display of royal inbreeding, they were uncle and niece.
The close blood ties between Margaret's parents came at a cost. Of their five children, three died in infancy. Only two survived: Margaret and her younger brother Charles, known in Spanish as Carlos.
Survival did not mean salvation for Charles. By his twenties, he was prematurely aged, balding, and plagued by a grotesquely deformed jaw. His mind seemed to wither as fast as his body, showing signs of early dementia. Contemporaries nicknamed him "the Bewitched," believing his condition was the result of sorcery.
Margaret and Charles's inbreeding coefficient was grotesquely high. Some estimates suggest they were as inbred as children born to siblings. Historians still debate whether Charles's condition was purely genetic or something else.
Margaret may have been luckier, but she was not completely unaffected. Though much healthier than her brother, she carried the Habsburg curse in her own way.
She was raised in the grandeur of the Royal Alcazar Palace, a world of opulence where every whim was catered to by an army of maids and servants. The infanta frequently indulged in sweets and chocolates, which she had to hide from the court physicians.
Beneath the luxury lay the suffocating constraints of the Madrid court, where every movement, word, and glance was dictated by unyielding royal etiquette. As a princess of the Habsburg dynasty, she received the finest education money and power could provide. She learned multiple languages, including German to converse with Habsburg cousins from the Austrian side, and some Latin, the sacred language of scholarship and the Roman Catholic Church.
As Margaret grew older, she could not ignore the glaring age gap between her parents. Her father was nearly 30 years older than her mother. If that detail disturbed her, she never showed it.
Age differences aside, her parents adored her. She was their prized jewel, the only truly healthy child their union had produced, and they showered her with affection. With her delicate features and lively spirit, Margaret captivated those around her. She was their little angel, a nickname whispered with adoration by family and friends.
Her parents commissioned one of Europe's greatest painters to immortalize her in a stunning portrait when she was just 5 years old. That portrait would become one of the most famous paintings in history. Velázquez's painting was once known as "The Family" but today is called "Las Meninas," which means "The Ladies in Waiting."
The painting depicts Margaret being waited on by several household staff who are fixing her dress. Among the many figures captured is Maria Bárbola, a courtier with dwarfism. In an era when those with her condition were often reduced to mere entertainment for the nobility, Velázquez did something radical. Instead of portraying her as a joke, he gave her depth, dignity, and a piercing gaze that suggests a complex inner world.
Velázquez himself appears in the masterpiece as a silent observer of the lavish yet rigid world of the Spanish court. Other people are seen in paintings and mirrors in "Las Meninas," including Margaret's parents. It was not the only famous painting of Margaret. Velázquez painted no fewer than five portraits of the princess in her youth, immortalizing her prettiness and royal elegance. She was one of the most painted young people in all of early modern Europe.
By the time "Las Meninas" was painted in 1656, when Margaret was just 5 years old, there was already growing discussion at the Spanish court about who she would marry. In the ruthless world of royal politics, marriage was never about love. It was about power, and emotions and personal desires meant nothing when dynasties were at stake.
As the daughter of the king of Spain, Margaret was a high-stakes chess piece in the brutal game of European diplomacy. Her future was decided long before she understood it. At one point, there was a suggestion that she could marry Charles Stuart of the English royal family, who was restored to the English throne as King Charles II of England, Scotland, and Ireland in 1660.
A marriage of this kind would have formed an unlikely alliance with the English at a time when France and Spain were bitter rivals for dominance of Western Europe. In the end, Charles instead married Katherine of Braganza, a Portuguese bride, in 1662. The collapse of negotiations for Margaret to marry Charles Stuart was primarily owing to King Philip's opposition.
Instead, Philip believed his daughter should marry a member of the Austrian side of the Habsburg family. He seemed to show no concern that this marriage would deepen the family's inbreeding. It was simply how the Habsburgs kept power in their grip.
Margaret had no say in her fate. When negotiations between Madrid and Vienna began, she was likely blissfully unaware of the consequences this union would bring. She was still just 11 years old when it was announced at the royal court that she would marry Leopold of the House of Habsburg.
Like her mother before her, Margaret was now destined to continue the incestuous Habsburg tradition. She was going to marry a very close family member, a man who was both her first cousin and her uncle. Leopold was her mother's younger brother and had succeeded to become Archduke of Austria, King of Hungary, Croatia, and Bohemia, and Holy Roman Emperor in quick succession in the late 1650s.
Even in early modern Europe, there were some standards around when a child was old enough to marry. Margaret was betrothed to her uncle early in 1663 but was deemed too young for the marriage to take place at that time. It was not until April 1666, when she was nearing her 15th birthday, that Margaret set off from Madrid to travel to Vienna.
A six-month tour followed, and the Spanish royal party only arrived in Vienna in December 1666. The marriage ceremony took place a few days later, on December 12. It was a magnificent event attended by many of Europe's most powerful royals and dignitaries, with no expense spared. Celebrations raged on throughout 1667.
Behind the splendor, a dark fate was already unfolding. Life in Vienna was peculiar and sometimes difficult for Margaret. To begin with, she and her new husband had a strange marriage. They did not try to ignore their close blood relationship, and she actually called him "Uncle."
Despite this unorthodox situation, they got along. They enjoyed some of the same pursuits, including art and music, and Leopold did his best to make sure Margaret was comfortable in her new surroundings. It was also common for royals like Margaret, when they left their homeland to marry a foreign ruler or prince, to bring along members of their old household staff. She would have had some familiar faces around her at the court in Vienna as she acclimatized to her new life.
Despite this, Margaret remained deeply homesick, clinging to her Spanish roots and doing little to improve her German. As time passed, her once delicate beauty began to fade. Her complexion grew paler, her features more fatigued, and the characteristic Habsburg jaw became more pronounced.
The marriage was troubled in other ways too. Margaret became pregnant almost immediately after arriving in Vienna and gave birth to a boy named Ferdinand in September 1667. He only survived for three and a half months, dying in January 1668.
Their luck seemed to change with the birth of their next child, a daughter named Maria Antonia, born in January 1669. She would be the only one of Margaret's children to survive. Two others were not so fortunate. A son, John Leopold, was born on February 20, 1670, but died within hours. Another daughter, Maria Anna, lived just two weeks before passing away in February 1672.
This devastating pattern was a sign of things to come. Margaret's difficult series of pregnancies were partly owing to her own health problems. Although she had been a much healthier child than her brother, she did have some growing health issues in the years leading up to and following her arrival in Vienna.
When she arrived in the Austrian capital late in 1666, people there quickly began commenting on her frequent illnesses. For a time, many observers put this down to the constant strain of pregnancy. In just six years, she endured six pregnancies, including four live births and two miscarriages, each leaving her weaker and more depressed than before.
As time passed, it became clear that something more sinister was at play. Margaret was often confined to her bed even when she was not pregnant. Physicians diagnosed her with an enlarged thyroid gland, but in the 17th century there was no cure, and her condition only worsened.
Things really went downhill for Margaret in the early spring of 1673. She had a three-week-long attack of stomach pains, then developed a fever. Documents written by foreign ambassadors at the court in Vienna at this time indicate that many were seriously concerned she would die.
By early March she had difficulties breathing, and on March 10 a confessor was called in to hear her last confession and give her the sacrament. Just two days later, on March 12, Margaret died at the tender age of 21. An autopsy revealed a heartbreaking truth: she was carrying another baby boy at the time of her death.
Her life, cut tragically short, ended in the Imperial Crypt in Vienna, where she was laid to rest. The death of the archduchess and Holy Roman Empress resulted in a lengthy mourning period at the Austrian court. The funeral services stretched on for weeks into April.
Leopold was devastated by his wife's untimely death. However, this did not stop him from marrying again by the end of the year. His new wife was Archduchess Claudia Felicitas of Austria, a member of the Tyrolean branch of the Habsburgs. For Leopold, the marriage was not about love. It was about survival. The dynastic game had to continue, and more heirs were desperately needed, preferably male, to ensure the Habsburg reign could endure.
After Margaret's death, her rights to the Spanish throne were passed to her only surviving daughter, Maria Antonia. When Maria Antonia herself died in 1692, her rights were inherited by her only surviving son, Prince Joseph Ferdinand of Bavaria. However, Joseph Ferdinand's untimely death in 1699, coupled with King Charles II's failure to produce an heir, would trigger a succession crisis that plunged Spain and all of Europe into a brutal war that lasted nearly 15 years.
It was a crisis that perhaps could have been avoided if the Habsburgs had not destroyed themselves from within due to their incestuous practices.