Henry, Earl of Lancaster, one of the principals behind Edward II's deposition, tried to overthrow Mortimer, but the action was ineffective as the young king passively stood by. Then, in March 1330, Mortimer ordered the execution of Edmund, Earl of Kent, the half-brother of Edward II. After this execution Henry Lancaster prevailed upon the young king, Edward III, to assert his independence. In October 1330, a Parliament was summoned to Nottingham, just days before Edward's eighteenth birthday, and Mortimer and Isabella were seized by Edward and his companions from inside Nottingham Castle. In spite of Isabella's entreaty to her son, "Fair son, have pity on the gentle Mortimer," Mortimer was conveyed to the Tower. Accused of assuming royal power and of various other high misdemeanours, he was condemned without trial and hanged at Tyburn on 29 November 1330, his vast estates forfeited to the crown. His body hung at the gallows for two days and nights in full view of the populace. Mortimer's widow Joan received a pardon in 1336 and survived until 1356. She was buried beside Mortimer at Wigmore, but the site was later destroyed.