Maria of Castile (14 November 1401 – 4 September 1458) was Queen of Aragon and Naples as the spouse of Alfonso V of Aragon. Maria acted as the regent of Aragon during the reign of her spouse, as he was absent during most of his reign; her regencies lasted between 1420 and 1423 and between 1432 and 1458. She was also briefly Princess of Asturias in her own right as the heir presumptive to the throne of Castile. She succeeded her father, Henry III of Castile, as Princess of Asturias in 1402. Childhood Maria was the eldest child of King Henry III of Castile and Catherine of Lancaster. Her godmother was her mother's aunt, Maria de Ayala, a nun and illegitimate daughter of King Peter of Castile. She grew up in an entirely Castilian household in which she lived until her marriage, which was unusual for a royal daughter destined to marry a foreign prince. Her education was supervised by the great steward, Pedro González de Mendoza, while her governess was Inés de Ayala y Toledo, 3rd Lady de Casarrubios del Monte. As the King's eldest child, Maria was granted the title of Princess of Asturias, the title reserved for the first-in-line to the throne. Her father had her formally recognised as heir presumptive at the Cortes of Toledo on 6 January 1402. At the same time, she was betrothed to her first cousin, Alfonso, the son of her paternal uncle Ferdinand, as a way to strengthen her status. However, the birth of her brother John (the future king) displaced the Princess in the line of succession; from that moment on, she was merely an infanta. Her childhood was quite happy by all accounts; the frailty of her health was not evident until she was a married adolescent. Her father died when she was four, leaving the crown to her only brother, John II, and making her heiress presumptive again. Her mother, Queen Catherine, governed the Crown of Castile as regent during King John II's minority and the Infanta was able to observe her mother's statesmanship. The queen mother's political actions would later make Maria aware of her own responsibilities and prerogatives as a queen and as a regent. Mother and daughter were very close and remained in frequent correspondence even after the latter's marriage. Marriage The engagement of Maria and Alfonso was not formalised until she was seven, but