 When John was forced to sign Magna Carta, Llywelyn was rewarded with several favourable provisions relating to Wales, including the release of his son, Gruffydd, who had been a hostage since 1211.The same year, Ednyfed Fychan was appointed seneschal of Gwynedd and was to work closely with Llywelyn for the remainder of his reign.Llywelyn had now established himself as the leader of the independent princes of Wales, and in December 1215, led an army which included all the lesser princes to capture the castles of Carmarthen, Kidwelly, Llanstephan, Cardigan and Cilgerran.