[2] 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.

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.

[3] Maria was given a splendid dowry in form of land and revenues, while Alfonso was raised to the rank of infante of Castile.

The infantes of Aragon, her brothers-in-law, Henry, Peter and especially the meddlesome John would prove problematic and pertinent to Maria's regency.

Their relationship began visibly deteriorating in 1423, after Alfonso's return from Naples and upon learning that her husband's Italian lover, Giraldona Carlino, had given him a son, Ferdinand.

[7] Less than one year later, on 1 April 1416, King Ferdinand I died, leaving the crown to Maria's husband and making her Queen of Aragon.

[11] As the King was absent from Aragon almost his entire reign, the Queen was the de facto ruler of the kingdom, holding the formal title of lieutenant-general.

While her personal retinue included many Castilians, Maria strategically appointed only Aragonese to the offices during her regency, which contributed to her popularity and the smooth functioning of her court.

[13] In 1454, after her brother's death, the Queen of Aragon travelled to Castile to negotiate with its new king, her nephew, Henry IV.