Catherine of Lancaster (Castilian: Catalina; 31 March 1373 – 2 June 1418) was Queen of Castile by marriage to King Henry III of Castile. She governed Castile as regent from 1406 until 1418 during the minority of her son. Queen Catherine was the daughter of John of Gaunt, 1st Duke of Lancaster, and his second wife, Constance of Castile (the daughter and heir of King Peter of Castile, who died at the hands of his half brother Henry II). She was born in Hertford Castle, her father's chief country home, on 31 March 1373. Catherine became Queen of Castile through her marriage to Henry III. Marriage After King John I of Portugal defeated King John I of Castile at the Battle of Aljubarrota, South Leiria, in 1385, fully establishing Portuguese independence, Catherine's parents, the Duke and Duchess of Lancaster, were encouraged to press their claim for the Castilian throne. In 1386, Catherine joined her parents in an expedition to Castile to claim the throne. England and Portugal entered into an alliance against Castile in 1386 and solidified their ties through the marriage of King John I and Catherine's half-sister, Philippa. John of Gaunt had ruled Santiago de Compostela, Vigo, and Pontevedra with ease, but had to withdraw to Portugal in 1387 because of an unsuccessful invasion of León. It was then that he accepted the proposal of King John I of Castile, to marry Catherine to his son, the future Henry III, and that Constance, Duchess of Lancaster, should renounce all claims to the Castilian throne. A final treaty in regards to this proposal was ratified at Bayonne in Gascony on 8 July 1388. The marriage helped to restore a semblance of legitimacy to the Trastámara line. Furthermore, together with the Truce of Leulingham and the one made at Monção Municipality, the betrothal helped to end the Spanish period of the Hundred Years War. On 5 August 1388, the 15-year-old Catherine announced that she entered into the marriage freely and fully accepted the treaty. The treaty had included a dower of the towns of Soria, Almazán, Atienza, Deza, and Molina. By 17 September 1388, Catherine was married to the nine-year-old Henry in Palencia Cathedral. Her husband took over the throne after the death of his father in 1390, but only in 1393 was he declared of age and began to rule. Catherine's only contribution to Henry's rule was the bearing