Maurice married Alicia, daughter of Arnulph de Montgomery, brother of Robert Earl of Shrewsbury, and by that lady had four sons. The eldest was known as Gerald Fitz-Maurice, who in due course succeeded his father, and was created Lord Offaly. Having married Catherine, daughter of Hamo de Valois, Lord Chief Justice of Ireland, he had a son, named Maurice after his grandfather. This Maurice died in 1257, leaving two sons, Thomas and Gerald. Thomas, generally called "Tomas Mor," or Great Thomas, on account of his great valour and signal services in the battlefield, succeeded his father as Lord Offaly. He married the only daughter of Thomas Carron. This lady brought him the Seigniory of Desmond as a dowry. By her Thomas Lord Offaly had an only son, John, who, according to Colin Fitzgerald's supporters, was first Earl of Kildare and married first, Marjory, daughter of Sir Thomas Fitz-Antony, by whom he had issue - Maurice, progenitor of the Dukes of Leinster. John married, secondly, Honora, daughter of Hugh O'Connor, by whom he had six sons, the eldest of whom, according to the Irish-origin theory, was Colin Fitz-Gerald - but who, if the Fitzgerald theory had not been a pure invention, really ought to have been called Colin Fitz-John, or son of John - the reputed ancestor of the Mackenzies. This, briefly stated, is the genealogy of the Fitzgeralds as given by the supporters of the Irish origin of the Mackenzies, and it may be right or wrong for all we need care in discussing the origin of the Mackenzies. Its accuracy will, however, be proved impossible. According to the true genealogy, Thomas, who was the third son of Maurice, married Rohesia, heiress of Woodstock, near Athy, and daughter of Richard de St. Michael, Lord of Rheban. By this lady he had an only son, John, who succeeded as 6th Baron Offaly, and was in 1316 created 1st Earl of Kildare. John married Blanche, daughter of John Roche, Baron of Fermoy; not the two ladies given him in the Fitzgerald-Mackenzie genealogy. The real authentic genealogy of the Fitzgeralds, from whom the Dukes of Leinster and other Fitzgerald families are descended, is as follows: The first, I. OTHO, known as "Dominus Otho," belonged undoubtedly to the Gherardini family of Florence. He passed into Normandy, and in 1057 crossed into England, became a favourite with Edward the Confessor, and obtained extensive estates from that monarch. He had a son II. WALTER FITZ OTHO, or son of Otho. He is mentioned in Domesday Book in 1078 as being then in possession of his father's estates. He was Castellan of Windsor and Warden of the Forests in Berkshire. He married Gladys, daughter of Rhiwallon ap Cynfyn, Prince of North Wales, and had three sons, the eldest being