The family was a branch of the FitzMaurice/FitzGerald Dynasty commonly known as the Geraldines and related to the now extinct Earls of Desmond who were granted extensive lands in County Limerick by the Crown.
There is confusion as to Honora's parentage, as one source claims her to be the daughter of Phelim MacHugh O'Connor Don, of the family of the Kings of Connacht.
[9] This Desmond family are descended from Maurice FitzGerald, Lord of Llanstephan, a companion-in-arms of Strongbow Richard de Clare, 2nd Earl of Pembroke, the Norman conqueror of Ireland.
He went to Ireland in 1168, being sent with ten knights, twenty esquires, and one hundred archers, to assist Dermot MacMurrough, king of Leinster.
[5] Maurice was the second son of Gerald de Windsor, Constable of Pembroke, Wales and his wife given to him by Plantagenet Norman English King Henry II, the South Welsh Princess Nesta or Nest ferch Rhys thus descended from Howell the Good, king of the Britons who codified Welsh Law.
John Fitz-Thomas FitzGerald, by virtue of his royal seigniory as a Count Palatine, created three of his sons by the second marriage, knights; and their descendants have been so styled in acts of parliament, patents under the great seal, and all legal proceedings, up to the present (1910) time.
[5] According to another legend, in the early 16th century under Elizabeth I, England set about enforcing loyalty in the western parts of Ireland.
[citation needed] The 17th Knight, Gerald FitzGerald, was a Member for County Limerick in the Irish Patriot Parliament of 1689, called by James II during the Williamite war.
[citation needed] Under the Penal Laws of the 18th century, the Knights converted to the Church of Ireland to preserve their property.
[citation needed] Following the war of independence and during the ensuing Civil War, in the early 1920s, Irish Republican Army (IRA) soldiers, from nearby North Kerry came to the 27th Knight Desmond FitzJohn Lloyd FitzGerald to tell him that no one whose title to land came from the English Crown could keep their land.
The Knight immediately produced a document in Latin, supposedly from Duke of Normandy, indicating that his title did not originate from the English Crown at all.
Another version of the incident relates how the then Knight, who was an invalid and used a wheelchair, refused to leave the mansion when ordered to do so, as the IRA intended to set it alight.
that there is an heir male of the body needing to prove their claim to the title, surviving through the 24th Knight of Glin, Lt. Col. John Fraunceis FitzGerald's second son Edmond Urmston McLeod FitzGerald, who was born in 1817 at Glin Castle and who married Ellen Sullivan, born in Ireland, 1822, died in Ogdensburg, New York, United States, in December 1895.