The castle passed to John's grandson, also called John, who, in 1304, married Joan de Barr. The marriage broke down but John's attempts to gain a divorce in 1316 failed in the law courts. John blamed Thomas, the Earl of Lancaster, for this and in response he kidnapped Thomas' wife; Thomas then retaliated by seizing Conisbrough Castle. Edward II intervened in the dispute and confirmed Thomas as the new owner of the castle. In 1322, however, Thomas rebelled against the King and was executed, resulting in Edward taking control of Conisbrough himself. The King visited the castle in 1322, and spent 40 marks on repairing both Conisbrough and the neighbouring castle of Pontefract. Edward was overthrown by his wife Isabella in 1326 and the castle was returned to John. John had hoped to pass the property to his mistress and two illegitimate sons, but he outlived them and on his death in 1347 it reverted to the control of the Crown.