Situated about twelve miles west-by-north of Dublin, this ancient fortress of the Pale was the chief stronghold of the Kildare branch of the Geraldines. It was built by Maurice FitzGerald (the first of the great family to settle in Ireland) to protect the lands of Offaly, granted to him in 1176 by Strongbow in lieu of part of Wexford which King Henry wished to retain.
From the excellency of the twelfth-century masonry, the great keep, with walls some 8 feet in thickness, and the gate-house, are the best preserved parts of the ruin. The large corner tower and three round arches adjoining belong to the thirteenth century, while the fifteenth century is represented by an oblong tower, now used as the belfry of the Episcopalian Church. The rest of the buildings which connected these, now isolated, structures have almost entirely disappeared.
The fortress was surrounded on two sides by water, being at the junction of the River Lyreen, a tributary of the Liffey, and a smaller stream.
In 1248 we read that Luke, Archbishop of Dublin, erected the chapel of Maynooth into a prebend of St. Patrick’s Cathedral at the request of Maurice, second Baron of Offaly. This building, which was once the castle chapel, is now the parish church.
At the beginning of the fourteenth century Maynooth seems to have been the favourite residence of the FitzGerald family. John, the 1st Earl of Kildare, and Thomas, the 2nd Earl, both died there (1316 and 1328). The latter bequeathed the castle to his wife. It is described as being “built of stone, with numerous offices partly of stone, and two gates, one leading to the town, and the other to the garden.”
The castle was added to in 1426, and is said to have been “one of the largest and richest Earl’s houses in Ireland.”
In 1534 the Earl of Kildare, being Lord Deputy, was summoned to London, and appointed his son, Lord Offaly, Vice-Deputy in his absence. Upon a rumour that his father had been executed, Lord Thomas, who was very young, went into rebellion, and such nobles and chiefs as refused to join his standard he sent as prisoners to Maynooth.
A division of the English army, landing at Howth to raise the siege of Dublin Castle, was met by “Silken Thomas” with two hundred men. An engagement followed, in which Lord Offaly was victorious, and the survivors of the King’s troops were sent captive to Maynooth.
At this time the castle was splendidly fortified with men and ordnance.
Hearing that the whole English army was about to arrive, Lord Offaly left Maynooth in command of Christopher Paris, his foster-brother, and went into Connaught to raise forces.