"[1] He was born in 1238 in Wexford, Ireland, the second son of Maurice FitzGerald, 2nd Lord of Offaly and Juliana de Grenville.
[4] Maurice FitzMaurice and his nephew John, son of his brother Thomas,[5] captured the justiciar, Richard de la Rochelle, Theobald Butler IV, and John de Cogan I (whose son was married to Maurice FitzGerald III's sister, Juliana).
However, the Second Barons' War in England forced them to come to a temporary peace while they battled Montfortians in the English Midlands in 1266.
[6] In May 1265, Maurice FitzMaurice was among the chief magnates in Ireland summoned to inform King Henry III of England and his son Prince Edward about conditions in the country, and again in June 1265.
These were the result of the private war between the Geraldines and Walter de Burgh, lord of Connacht (who was later made the 1st Earl of Ulster).
Maurice's contingent joined the main army of English settlers jointly commanded by his son-in-law, Thomas de Clare, Lord of Inchiquin and Youghal, who had been made Lord of Thomond earlier that same year, and Sir Geoffrey de Geneville, Maurice's successor as Justiciar of Ireland.
Emmeline Longespee then fought until her death to claim her dower against her daughter, Juliana, her step-daughter, Amabilia, and John FitzGerald, who would be created 1st Earl of Kildare on 14 May 1316.