http://www.thepeerage.com/p15142.htm#i151417

Lady Joan de Burgh was the daughter of Richard de Burgh, 2nd Earl of Ulster and Margaret de Burgh.1 She married, firstly, Thomas FitzJohn FitzGerald, 2nd Earl of Kildare, son of John FitzThomas FitzGerald, 1st Earl of Kildare and Blanche de la Roche, on 16 August 1312 at Greencastle, County Down, Ireland.2 She married, secondly, Sir John Darcy, 1st Lord Darcy de Knayth, son of Sir Roger Darcy and Isabel d'Aton, on 3 July 1329.3 She died on 23 April 1359.1

    From 16 August 1312, her married name became FitzGerald.1 As a result of her marriage, Lady Joan de Burgh was styled as Countess of Kildare on 12 September 1316. From 3 July 1329, her married name became Darcy.