In Harleian Collection book "Calendar of Documents relating to Ireland" AD1293-1301, page 158, #344, November 15th 1296 - "The King (of England) pardons to John FitzThomas (FitzGerald), for his service in the war of Scotland, the King's suit of peace for all homicides, robberies, and transgressions in Ireland, except those touching Richard de Burgh, Earl of Ulster. (Letters Patent 24, Edward I, memo 1). This may relate to the feud between the FitzGeralds & Burghs in AD1294.
#354.Nov. 26th 1296 - "Whereas John FitzThomas (FitzGerald) has testified before the King (of England) that Sir William Cadel of Cloyneynam, Reginald Berneval, Richard Cadel, and William, son of Robert Cadel, have well and manfully served the King in the war of Scotland, the King pardons to them the King's suit of peace for homicides, robberies, and transgressions in Ireland. (Letters patent, 25 (King) Edward I., pt.1, memo.24.)
John FitzThomas FitzGerald (b.c.1250 d. Sept.13th 1316), was created the 1st Earl of Kildare on May 14th 1316 by King Edward II of England.
The time-slot for the above perhaps makes him the person who captured the fort for the King and then was bestowed with the Earldom of Kildare, the premier Earldom of Ireland.