They were also permitted servants to wait upon them as the King's half-siblings. In 1442, their half-brother the King began to take an interest in their upbringing. Sometime after March 1442, Jasper and his brother were brought to live at court. Henry arranged for the best priest to educate them intellectually and morally. The brothers also received military training; when they grew up they were given military positions. Jasper was recognised as Henry VI's uterine brother when, on 23 November 1452, he was created Earl of Pembroke. Owen Tudor was released from prison, most likely thanks to his stepson Henry VI, who after providing for his stepfather, also provided for his two half-brothers. It is not clear whether Henry VI had known of the existence of his half-brothers until his mother told him while she was dying in Bermondsey Abbey. It was after her death that Henry would begin to care for them and eventually raise them to the peerage by giving both brothers earldoms. Jasper became Earl of Pembroke on 23 November 1452, the seventh creation. In turn, Edmund and Jasper swore unwavering loyalty to Henry and fought and promoted him and his Lancastrian family's interests persistently throughout their lives. Owen and Catherine's marriage was not recognised by the authorities, in large part due to the secrecy under which it was accomplished, and so the legitimacy of Jasper and his two (or three) siblings was questionable. However, Jasper enjoyed all the privileges appropriate to his birth, including being invested as a Knight of the Garter. After 1485, he would describe himself as the “high and mighty Prince Jasper, brother and uncle of Kings, Duke of Bedford and Earl of Pembroke”. During his time at court, Jasper constantly tried to work with the Duke of York and other nobles in order to try to stop the infighting between the two houses. It was after the death of his elder brother, Edmund, that Jasper took over the responsibility of maintaining the Lancastrian ties within Wales. Along with this, he took into his care his sister-in-law and infant nephew. On the accession of the Yorkist King Edward IV in 1461, he was subject to an attainder for supporting his Lancastrian half-brother, the deposed King Henry, to whom Jasper was loyal. He strove to place his half-nephew Prince Edward of Lancaster on the throne and provided absolute loyalty to his royal half-brother and Margaret of Anjou, his half-brother's wife.