#trastamara.

After Queen Isabel’s death in 1504, Juana inherited the throne of Castile. However, her mental health—or at least the perception of it—became a major issue. She was described as melancholic, obsessive, and prone to deep grief, especially after the death of her husband Philip the Handsome in 1506. Her father, Fernando, and later her son, Carlos V, used her supposed instability to control Castile politically, effectively confining her in the palace at Tordesillas for decades.

In his dispatches to Emperor Carlos V, Eustace Chapuys recorded that Katherine often asked after her sister’s health and situation in Tordesillas. He added that Katherine “loved her sister tenderly, and mourned her misfortunes as if they were her own.”

Katherine of Aragon and her sister María

Katherine of Aragon spent her early years in a household that was at once intensely regal and deeply religious. Among her elder sisters, it was Maria—born three years before her—who became Katherine’s closest companion. While Isabel and Juana were older and often drawn into the more formal responsibilities of court life, Katherine and Maria shared the more intimate rhythms of childhood together.

The sisters were nurtured chiefly within the Castilian court, where Queen Isabel devoted particular care to the education of her daughters. Katherine and María shared their lessons in the same schoolroom, slept within the same chamber, and were inseparable companions in the diversions and pastimes permitted to royal children. They took part in solemn processions, festive celebrations, and the entertainments of the court, from banquets to the grand spectacles of jousts and pageantry. More often than not, Katherine and María were placed side by side, attending Mass together and uniting with their parents in prayer and devotion.

From an early age, Katherine and María were also introduced to the charitable duties expected of members of the royal family. Under the supervision of their tutors and ladies-in-waiting, they took part in simple acts of mercy—such as giving alms, preparing offerings, or assisting in small works of relief for the poor and sick.

In their youth, the royal children did not grow up in one single palace but instead followed their parents as part of the itinerant court across both Castile and Aragon. Fernando and Isabel frequently traveled throughout their kingdoms to assert royal authority, administer justice, and oversee governance, while also directing military campaigns against the kingdom of Granada and conducting diplomatic negotiations with foreign envoys. Katherine and María witnessed as young girls the dramatic events of their parents’ reign as the conquest of Granada or the expulsion of the Jews. The sponsorship of Columbus and subsequent voyages to the New World unfolded during their childhood. The royal children were largely shielded from witnessing the harsh realities of the Inquisition.

As infantas of Aragon and Castile, their hands in marriage was important in European politics. Isabel and Fernando entertained the idea of marrying María to James IV of Scotland. This was at a time when Katherine's marriage to Arthur of Wales was being planned. The Catholic Monarchs thought if Maria was Queen of Scotland, the two sisters could keep the peace between their husbands. These plans, however, came to nothing.

Katherine and María watched their elder siblings leave home—to marry, begin families, and, in the cases of Isabel and Juan, die far too young. Isabel’s newborn son, Prince Miguel, was raised at the Castilian court under the devoted care of Queen Isabel and his two teenage aunts, who came to know him less as a nephew than as a little brother growing up among them. Yet Miguel’s position within the dynasty carried extraordinary significance: as the child of King Manuel of Portugal—Maria’s own betrothed—he was simultaneously her nephew, her future stepson, and the living embodiment of the hoped-for union of Castile, Aragon, and Portugal. The court was once again draped in mourning when the little prince died at the tender age of two. For all who had cherished him, the grief was profound. Katherine and Maria must have been a great comfort to each other, and to their mother, during this trying time, but even this was destined to end.

In the autumn of 1500, the Catholic Monarchs prepared to part with yet another daughter. María was wed to Manuel of Portugal by proxy marriage in Granada, so she was legally his wife before ever leaving Castile. After leaving the Alhambra, her parents and sister traveled with her the short distance to Santa Fe. They remained there for about a week, staying close until the last possible moment. There, the final farewells took place. María received her parents’ blessing, embraced them and her sister, and then continued her journey west to Portugal. For Katherine, it was another painful goodbye to a sister. Now María was being carried away into another kingdom. The royal family turned back toward Granada.

Within the sad walls of the Alhambra, Isabel of Castile found consolation in the daughter who remained at her side. Katherine, still only fourteen, became her mother’s comfort. Devout, steady, and tender, she lightened her mother’s burden in the twilight years of Isabel’s life, even as she herself awaited the summons that would carry her across the sea to England and her own uncertain destiny.

The limited surviving correspondence between Katherine and her sister María demonstrates the persistence of their early closeness into adulthood. Katherine’s letters often conveyed affection and longing for news from Spain, reflecting her isolation in England, while María’s replies offered reassurance and updates from their natal family. Beyond emotional support, their exchanges occasionally addressed courtly, religious, and diplomatic matters.

⚖️ Catherine of Aragon: The First Female Ambassador

Catherine of Aragon is generally acknowledged as the first woman in European history to hold an official ambassadorial appointment — that is, to be formally accredited by one sovereign power to another. Between 1507 and 1509, she served as her father Ferdinand II of Aragon’s resident ambassador at the English court, during the protracted negotiations preceding her marriage to Prince Henry, the future Henry VIII.

This was not an informal or honorary role: she was the official diplomatic representative of Aragon, with authority to negotiate political and financial matters with King Henry VII and his council. Contemporary English observers did indeed find it unusual for a woman to hold such a significant diplomatic position. The Venetian ambassador at the time noted this as an exceptional circumstance.

The crucial distinction lies in official diplomatic accreditation. Before the sixteenth century, “ambassadors” were almost always male clerics or nobles formally commissioned by their rulers. Women could negotiate, mediate, or influence, but Catherine’s appointment by her father as ambassador to England marked a legal and administrative first.

Other noblewomen before Catherine acted as envoys or negotiators — but they did so informally or as regents / consorts, not as formally appointed ambassadors. Many acted as de facto diplomats — sending letters, arranging marriages, and conducting negotiations — but again, these were extensions of their dynastic or consort status, not formal offices in international law.

Catherine of Aragon actively intervened in ambassadorial appointments, marriage portion negotiations, and diplomatic matters with England. Thus, although the modern title “ambassador” may not have been precisely the same as we use today, she functioned as a diplomatic agent/representative of her father’s crown to the English court. She maintained an active diplomatic correspondence with her father. Many of her letters to Spain were written in her own hand and composed in a complex cipher, carefully employed to safeguard confidential political information from interception or unauthorized reading.