General Notes

In A.D. 1168, Dermot MacMorrogh, King of Leinster, driven from his territory by Roderick O'Conor, High King if Ireland, sought assistance from the Norman-Welsh and succeeded in enlisting in his cause Richard de Clare, Earl of Pembroke (called Strongbow). Having reached St. David's, on his way back to Ireland, Dermot was hospitably received by David fitzGerald (son of Gerald of Windsor), Bishop of the diocese. According to Burke's Peerage, the Bishop persuaded his brother, Maurice fitzGerald, and his half-brother, Robert fitzStephen to assist MacMorrough with their forces.
Sometime after achieving success in that campaign, Strongbow granted to Maurice fitzGerald, known as "The Invader of Ireland",  the middle cantred of Offelan, in which Naas was situated. Offelan was a district quite distinct from Offaly.
Maurice married Alice de Montgomery and had six sons:
1. William fitzMaurice, Baron of Naas. Confirmed in his lands in Offelan in 1185.
2. Gerald fitzMaurice, 1st Baron of Offaly, ancestor of the Dukes of Leinster.
3. Thomas fitzMaurice, Lord of Connello, Co. Limerick. d. A.D. 1213. Ancestor of the FitzGeralds, the Earls of Desmond, the White Knight, the Knight of Glin, the Knight of Kerry, the FitzMaurice Lords of Kerry, etc.
4. Maurice fitzMaurice of Kiltrany (now Burntchurch), Co. Kilkenny. Ancestor of the Barons of Burntchurch.
5. Alexander fitzMaurice, d.s.p.
6. Robert fitzMaurice.
Burke's Peerage  (1970)