FitzGerald, Maurice (‘Muiris Ruadh’) (d. 1268), magnate, lord of Offaly, was the only son and heir of Gerald fitz Maurice FitzGerald (d. 1243), the eldest son of Maurice FitzGerald (qv) (d. 1257), baron of Offaly and justiciar of Ireland. His inheritance of Offaly from his grandfather was assured in 1257 after his uncle, Maurice fitz Maurice FitzGerald (qv) (d. 1286) quitclaimed his rights to the barony on receipt of lands in Connacht from his father. Despite this, however, custody of his wardship was the subject of a dispute between the countess of Lincoln, one of the Marshal heiresses, and his uncle. He probably came of age before May 1262. He was summoned to England in 1265 to advise the king and the Lord Edward about the state of Ireland. He was closely associated with his uncle when fitz Maurice seized the justiciar, Richard de la Rochelle (qv), and other members of the king's council in Ireland in December 1264 during a short-lived but very destructive quarrel with Walter de Burgh (qv), the earl of Ulster. Rochelle, Theobald Butler (qv) (d. 1285), and the others were imprisoned in his castles of Lea and Dunmase in Offaly. Any temptation on his part to make common cause with the Montfortians in England was removed in April 1265 when a compromise was agreed between de Burgh and the Geraldines. He seems to have accompanied his uncle, de Burgh, and others to England to fight on the royalist side in the civil war, and may have been present at the battle of Evesham in August. The following month he was sent with Hamo Lestrange on a disastrous expedition against the Welsh prince Llywelyn ap Gruffudd. At the siege of Kenilworth in the summer of 1266 he agreed to marry Agnes de Valence (qv), the daughter of William de Valence, lord of Pembroke and of Wexford, and Joan de Munchensey; they were married in August that year. He drowned while crossing the Irish Sea from England to Ireland about 25 July 1268.
Although his marriage to Agnes was childless, he produced an heir, Gerald fitz Maurice FitzGerald (c.1263–1287), from a previous marriage. Custody of his wardship and marriage was initially granted to Thomas de Clare (qv), who sold it in 1270 to William de Valence for a huge sum while both were on crusade. In 1283 William in turn sold it to Geoffrey de Geneville (qv), who married Gerald to his daughter Joan. That year, while still under age, Gerald led a contingent in Edward I's conquest of Wales and also began proceedings against his stepmother to recover estates in Limerick granted to her by his father. In 1284, while he was still in Wales, his castle of Lea was razed and the following year he was taken prisoner by the Irish in Offaly. He died childless in June 1287 but apparently on his deathbed started proceedings to transfer his barony and estates to his nearest male relative, a cousin, John fitz Thomas FitzGerald (qv), the future 1st earl of Kildare.