of Edward II's favorite Piers Gaveston, and helped secure Gaveston's 1308 banishment. The two were somewhat reconciled after Gaveston's return the next year, but in 1312 Warenne was one of the nobles who captured Gaveston. He was however unhappy about Gaveston's execution at the behest of the earl of Warwick, which pushed him back into the king's camp. The baronial opposition was led by the king's cousin Thomas, Earl of Lancaster, and he and Warenne became bitter enemies. Private war erupted between the two, and over the next few years Warenne lost a good part of his estates to Lancaster. In 1319, the King granted the Earl of Lancaster the towns of Conisboro and Sandal, along with the manors of Wakefield, Thorne, Hatfield, Sowerby, Braithwell, Fishlake, Dewsbury, and Halifax with their appurtenances, which were held of the King in capite, and which John de Warenne had previously held under Royal Grant. On May 17th 1326, these Yorkshire estates were then re-granted to Warenne, after the forfeiture of the Earl of Lancaster's estate in 1322. Warenne was one of the four earls who captured the two Roger Mortimers, the uncle and the nephew. In 1322 he was one of the nobles who condemned to death the Earl of Lancaster. Warenne and his brother-in-law Edmund Fitzalan, 9th Earl of Arundel, were the last two earls to remain loyal to Edward II after the rise to power of Queen Isabella and Roger Mortimer. After Arundel's execution he went over to the queen's side, urging Edward II's abdication in 1327. He was the guardian of his cousin Edward Balliol, and after Balliol lay claim to the Scottish throne, accompanied him on his campaign in Lothian. Balliol created Warenne earl of Strathern, but this was in name only for the properties of the earldom were held by the Scots. Warenne died in 1347 at Conisbrough Castle. His burial took place at the Priory church of St Pancras, in Lewes. John gave instruction in his will that he wished to be buried in an arch at the church which he had prepared near the high altar."Chapter Seventeen: A Disastrous Marriage and the End of a Dynasty". Connolly, S.B. (2021). Defenders of the Norman Crown: Rise and Fall of the Warenne Earls of Surrey. Barnsley: Pen & Sword History. p.218. Retrieved 08 July 2021. The date of his death recorded in his inquisition post mortems, ranges from