Lord Offaly was marching to the relief of his stronghold with an army of seven thousand men when the news of its fall reached him. At this, most of his forces melted away, and the rebellion became rather a series of raids than regular warfare.
At last, Lord Thomas, tempted by a promise of pardon, surrendered himself, and was sent prisoner to England. Here, after some months of captivity, he and his five uncles were beheaded at Tyburn.
There is a tradition that the last evening “Silken Thomas” ever spent at Maynooth he played the harp under the venerable yew which is now enclosed in the grounds of St. Patrick’s College.
A bill of attainder was passed in 1536 against the Earl of Kildare and his heirs; and Maynooth, being forfeited to the Crown, became a King’s castle. It seems to have been a favourite residence of the Lords Deputy at this time.
In 1552 Edward VI. restored Gerald, 11th Earl of Kildare, to his title and estates. His widow lived at Maynooth until her death; and it was in the castle garden that Lord Delvin was first approached by the Earls of Tyrone and Tyrconnell to join the insurrection in 1606. In a letter written by the Countess of Kildare she expresses her regret for such an occurrence.
After the death of the 14th Earl in 1612, Maynooth Castle seems to have fallen into a state of dilapidation on account of his son’s minority. It was restored by his guardian, the great Earl of Cork, who placed an inscription over the gateway recording its restoration, and bearing the date 1630.
In 1629 we hear of the Earl’s title deeds being preserved in the Council House, which was a stone building that stood on the site now occupied by the President’s house of St. Patrick’s College. It was removed about 1780. The doorway is still preserved in a school of the town, and the council table, bearing the date 1533, stands before the Duke of Leinster’s residence at Carton.
The 12th Earl of Kildare lived at Maynooth until civil war broke out in 1641. Shortly after hostilities began the castle was plundered and the valuable library destroyed.
In 1643 Captain Michael Jones, under the Marquis of Ormond, held possession of the fortress; and in 1644 the Earl of Kildare asked for powder and men to increase its defence, he having taken down the spouts to make bullets.
In 1647 General Owen O’Neill sent a detachment from Trim, which carried the castle by assault. Twenty-six men of the garrison and some officers were hanged, and the fortress dismantled.