[8] They achieved power through colonisation and the conquest of large swathes of Irish territory by the sons and grandsons of Gerald de Windsor (c. 1075 – 1135).

His father, Baron Walter FitzOther, was the first Constable and Governor of Windsor Castle for William the Conqueror, and was the Lord of 38 manors in England, making the FitzGeralds one of the "service families" on whom the King relied for his survival.

The FitzGeralds claim kinship with the Tudors who descended from the same Welsh royal line as Princess Nest's father, Rhys ap Tewdwr, King of Deheubarth.

In his poetry, Henry Howard, Earl of Surrey, a cousin of Anne Boleyn, also referred to Countess Elizabeth FitzGerald, (1527–89) as "Fair Geraldine", alluding to her family's Italian ancestry through the Gherardinis of Florence.

During the Italian War of 1521–1526, James FitzGerald, 10th Earl of Desmond, conspired with the Venetians and King Francis I of France, of Château de Chambord, against the Habsburgs, Tudors and Medicis.

[14] Another notable rebel was Commander James FitzMaurice FitzGerald, who led the Desmond Rebellions against the Tudors, and negotiated with Catherine de' Medici with the ambition of making her son, Henry III of France, the new King of Ireland.

[18][19] Although made Lord Chief Justice of Ireland in 1367,[19] Gerald wrote poetry in the Irish language, most famously the poem Mairg adeir olc ris na mnáibh[18] ("Speak not ill of womenkind").

Indeed, although an accomplished poet in Norman French,[19] Gerald was instrumental in the move by the Fitzmaurices and Fitzgeralds of Desmond toward greater use of the Irish language.

[18] Many members of the Fitzmaurices also became notable over the centuries, such as William Petty Fitzmaurice, 1st Marquess of Lansdowne, the Prime Minister of Britain who negotiated with Benjamin Franklin and secured peace with America at the end of the American War of Independence, or Henry Petty-Fitzmaurice, 5th Marquess of Lansdowne, Viceroy of Canada and India,[22] who became a half-nephew of Emperor Napoleon III, a step-grandson of Queen Hortense Bonaparte, and a great-grandson of Talleyrand, connecting the family with the Houses of Beauharnais, Talleyrand, and Bonaparte.

[citation needed] Gerald was the youngest son of another Norman adventurer, Walter fitz Otho, William the Conqueror's Constable for the strategic military fortress of Windsor Castle, as well as the King's Keeper of the Forests of Berkshire.

Domesday Book records Walter fitz Otho as tenant-in-chief of lands formerly held by conquered Englishmen in Berkshire, Buckinghamshire, Hampshire, and Middlesex.

Their grandchildren, Maurice FitzGerald, Lord of Lanstephan, Raymond le Gros and Philip de Barry were leaders in the Norman invasion of Ireland.

He became Archdeacon of Brecon, serving Archbishop Baldwin of Forde, a past tutor of Pope Eugene III's nephew, and worked with him at recruiting members for the Third Crusade of Richard the Lionheart against Saladin.

On many attempts Gerald tried to become the Bishop of St. Davids but failed, despite having met in Rome Pope Innocent III, who would later experienced the Sack of Constantinople.

[27] A priest named Maurice Fitzgerald was of passage in Florence at that time, with a Bishop of the Order of Saint Augustine, and has been able to enter in contact with one of his fellow kinsman, who then introduced him to other members of the Gherardinis.

[33] A letter written in 1566 by Girolamo Fortini, who was married to a daughter of Antonio Gherardini from Florence, to his brother in London, also stated that the Earl of Kildare was of the same family.

The English poet Henry Howard, Earl of Surrey, user of the sonnet form that would later be used by William Shakespeare, also referred to the ancestral seat of the Geraldines in Florence in his poem Description and praise of his love.

According to the magazine, the three families have maintained relationship among them even in recent times or in the past (for example with American President John Fitzgerald Kennedy).

[54] The FitzGerald dynasty was the subject of a poem called "The Geraldines" by Thomas Osborne Davis, the chief organizer and poet of the nationalist Young Ireland movement.