Balthasar Charles, Prince of Asturias

Balthasar Charles (17 October 1629 – 9 October 1646), Prince of Asturias, Prince of Girona, Duke of Montblanc, Count of Cervera, and Lord of Balaguer, Prince of Viana was heir apparent to all the kingdoms, states and dominions of the Spanish monarchy until his death.

Life
The only son of King Philip IV of Spain and his first wife, Elisabeth of France, Balthasar Charles was born in the Royal Palace of Madrid on 17 October 1629. He was baptized on 4 November 1629 in the Parish of San Juan, Madrid. His godparents were Infanta Maria Anna and Infante Charles, aunt and uncle of the newborn.

On 7 March 1632, Balthasar Carlos was sworn in before the Nobility of Castile as "His Majesty's Heir" and "Prince of these kingdoms of Castile and Leon, and others that are subject to these Crowns, united and incorporated", in a ceremony held at the Monastery of San Jerónimo el Real of Madrid.

Inés de Zúñiga y Velasco, Countess of Olivares (wife of the Count-Duke of Olivares), who was also chief lady-in-waiting to the Queen, served as the prince's governess. Later, his father appointed Juan de Isasi Idiáquez, a noble from Salamanca, as the prince's governor and tutor. Balthasar Charles received a humanist education, as well as instruction in military arts. Alonso Martínez de Espinar trained him in hunting, while Juan Bautista Martínez del Mazo gave him drawing lessons. He was reportedly an outstanding pupil, with an aptitude for languages.

Queen Elisabeth played a significant role in Balthasar Charles's upbringing and education, encouraging the prince to develop interests in music and theatre. She adored her son, and he was "devotedly attached" to his mother. She fell ill in October 1644 and would not allow Balthasar Charles or his sister, Maria Theresa, to approach her on her deathbed, stating, "There are plenty of Queens for Spain, but Princes and Princesses are rare". She died a day later, on 6 October 1644.

His father soon began diplomatic efforts to seek a bride for the prince: Archduchess Mariana of Austria, daughter of Holy Roman Emperor Ferdinand III and his paternal aunt, Maria Anna, and therefore his cousin, was chosen; they were betrothed in 1646. Another cousin, the daughter of his mother's sister, Henrietta Maria and her husband, King Charles I of England, Mary, Princess Royal, was also proposed as a potential bride, but nothing materialized due to religious differences.

After the Catalan revolt of 1640, Philip IV tried to win over Aragon to raise money and men for the new war front. One of the steps taken towards this end was to bring Balthasar Charles to be sworn as Crown Prince of the Kingdom of Aragón. The oath was held on 20 August 1645, when the Prince was fifteen years old, in the Cathedral of the Savior, Zaragoza, and he was titled as Prince of Gerona, Governor General of Aragon, Duke of Montblanc, Count of Cervera and Lord of the City of Balaguer. Shortly after, on 13 November 1645, Balthasar Charles was also sworn as heir to the Kingdom of Valencia.

In April 1646, Philip IV, wanting his son to be sworn in as heir apparent to the throne of Navarre, as he had been in Aragon the previous year, moved with him from Madrid to Pamplona, where, after recognizing the privileges of the kingdom of Navarre, the ceremony was solemnly celebrated on 3 May 1646.

Death
After the ceremony, the royal family moved to Zaragoza. On October 5, the eve of second anniversary of the death of Queen Elisabeth, Philip IV and Balthasar Charles attended Vespers in her memory. The prince fell ill that evening and stayed in bed on October 6 while the king attended the funeral. On October 7, the king wrote to his spiritual advisor, Sister Maria de Agreda, that the prince was suffering from severe fever and delirium, believed to be symptoms of smallpox. The disease spread rapidly, and two days later the Archbishop of Saragossa administered the Last Sacraments.

The Prince Balthasar Charles died on 9 October 1646, a few days before his seventeenth birthday. His remains were kept in Zaragoza until October 16, when they were transferred to the Monastery of San Lorenzo de El Escorial.

Because Philip IV was left without a son or a wife and had only one legitimate daughter, Balthasar Charles's death was "a shattering blow to the monarchy". The king, facing mounting pressure to remarry for the sake of securing a male heir, consented to a second marriage with his son's former bride-to-be, Mariana of Austria.

Depictions in art
The enduring image of Prince Balthasar Charles in art primarily stems from renowned portraits created by artists like Velázquez and Mazo. Notable among Velázquez's portrayals are "Prince Balthasar Charles on horseback," "Prince Balthasar Charles as a hunter," and "Prince Balthasar Charles with a dwarf" (located in the Museo del Prado and Museum of Fine Arts, Boston).

Moreover, many authors dedicated their work to the young prince. Examples include Diego de Saavedra Fajardo's most famous work, Idea of a Christian Political Prince represented in a Hundred Enterprises (1640), Cristóbal de Benavente y Benavides's Warnings for kings, princes and ambassadors (1643), and Baltasar Gracián's The Discreet (1646).