He was born about 1458, second son of Thomas Fitzgerald, 7th Earl of Kildare and Joan Fitzgerald, daughter of James Fitzgerald, 6th Earl of Desmond. He married Elizabeth Preston, daughter of Robert Preston, 1st Viscount Gormanston.Through his eldest daughter Margaret, who married Garrett Wellesley, he was an ancestor of the Duke of Wellington.
He resided at Laccagh in County Kildare, and despite his rebellion against the Crown his descendants retained his estates. He became of Ireland in 1484. After the downfall of the Yorkist dynasty the new King Henry VII confirmed him in office, but his loyalty to the new regime was deeply suspect.
In 1487 the impostor, claiming to be Edward Plantagenet, 17th Earl of Warwick, rightful heir of the House of York, appeared in Ireland.
He led his troops to England. But the rebellion was crushed at the Battle of Stoke, where Thomas was killed.
The Fitzgeralds retained their predominance in Irish politics for another 50 years: another reported remark of King Henry VII was that if all Ireland could not rule them, then they must rule all Ireland.
