The village of Geashill is situated in the barony of the same name, about eight miles south-east of Tullamore, in the King’s County. On a long ridge near are the ruins of the castle, adjoining a modern lodge usually occupied by the agent of the Digby estate. The ancient fortress is three storeys high, and a spiral stairway still leads to the summit, where there is an iron chair. An underground passage is said to run to the ruined Abbey close by.

The date of the castle’s erection by the Fitzgeralds is ascribed to the twelfth century, and in 1203 or 1204 the King commanded it to be delivered to William Marshall, Earl of Pembroke, as the guardian of Maurice, second Baron of Offaly, who was heir to Gerald FitzMaurice.

In 1305 the sept of the O’Dempseys slaughtered a great number of the O’Connors near the castle, and the following year the stronghold was destroyed by these native Irish. The Book of Howth says: “The Lord of Offalye builded the castle of Geschell” in 1307, so it was, no doubt, rebuilt this year by Thomas FitzMaurice, “the crooked heir,” who died in 1298, and who is supposed to have been prevented from inheriting as head of the family on account of some deformity. Juliana FitzGerald granted the castle to his son, who was her cousin, and afterwards 1st Earl of Kildare.

An inquisition was held at Kildare in 1282 upon the estate of the late John FitzThomas, when his heir, Thomas FitzMaurice, came of age. It was shown that the former had held lands from Maurice FitzGerald “for a moiety of the service of one knight whenever royal service should be summoned, rendering suit nevertheless at the court of the said Maurice FitzGerald at Geashill.”

Lord Leonard Gray and the chieftain O’Mulmoy seized the castle, and abbey of Killeigh in 1538. In both they found great stores of corn, part of which they burnt and part carried off.

On an ancient map of Leix, dated about 1563, both the castles of Lea and Geashill are marked as ruins, but in Sir Henry Sydney’s account of Ireland shortly afterwards he writes: “Geshell, in the King’s County, is very necessary to be had of the Earl of Kildare; it is a matter of consequence for her Majesty’s service in that county.”

James I. granted the barony of Geashill in 1619 and 1629 to Lady Lettice Digby, widow of Sir Robert Digby, of Warwickshire, as compensation for not inheriting as heir-general of the house of Kildare, she being the only child of the eldest son of the 11th Earl of Kildare. At the same time he created her Baroness of Offaly, and she lived quietly at Geashill from that date until 1642, when the great rebellion broke out and the Confederate Catholics laid siege to her stronghold.

A kinsman of hers named Henry Dempsy, brother of Lord Clanmalier, was in command, and despatched a letter “To the Honourable and thrice virtuous Lady, the Lady Digby,” demanding that she should surrender the castle to his Majesty and offering her and her household a free pass to wherever they wished, threatening at the same time if she did not comply to murder every Protestant in the town.

To this demand the Baroness sent the following answer: “I received your letter, wherein you threaten to sack this my castle, by his Majesty’s authority. I have ever been a loyal subject and good neighbour among you, and, therefore, cannot but wonder at such an assault. I thank you for your offer of a convoy, wherein I hold little safety; and, therefore, my resolution is, that being free of offending his Majesty, or doing wrong to any of you, I will live and die innocently, and will do the best to defend my own, leaving the issue to God. And though I have been, and still am desirous to avoid the shedding of Christian blood, yet, being provoked, your threats shall no wit dismay me.—Lettice Offaly.”

The castle was surrounded by bog and wood, and was, in consequence, somewhat difficult of access, so that upon receiving her letter the enemy retired to make more elaborate preparations for attack.

They collected a number of pots and pans, with which a man from Athboy constructed a cannon. It had to be cast three times before it was successful.

After two months the attackers returned to the castle with Lord Clanmalier in command. He despatched another letter demanding surrender to the brave lady, which received a spirited reply, reiterating her determination to endeavour to hold her own against all comers.

Upon its receipt they discharged the gun, which burst at the first shot, but a fusilade of muskets was kept up until the evening.

As the Baroness was looking out of one of the windows a ball struck the wall near her, and taking out her handkerchief, she contemptuously dusted the spot.

It is said that one of her sons, having fallen into the enemy’s hands, was brought before the castle in chains, with a threat that they would kill him unless she surrendered. She, however, replied that if they touched a hair of his head she would at once put to death a Roman Catholic priest who was within the walls.

At dark the enemy retired, again sending her a letter offering her terms, which received the same refusal as the others had done, and the messenger she sent was kept a prisoner.

Lady Offaly managed to let Sir Charles Coote, then at Naas, know that she needed assistance, and Philip Sydney, Viscount Lisle, at once set out from Dublin to her relief, accompanied by Sir Charles Coote, Sir George Wentworth, Lord Digby, the Baroness’s eldest son, and a considerable force of horse and foot.

Lady Offaly had also despatched an appeal for help to the FitzGeralds, but the letter fell into the enemy’s hands instead, who at once renewed the siege when they learnt of her straits.

As the English forces advanced the besiegers skirmished and retreated. The relieving party supplied the fortress with food and ammunition, but at Lady Offaly’s request she remained in the castle.

The following October she was again attacked by Charles Dempsie, but this time was shortly relieved by Sir Richard Grenville, and after this she retired to Cole’s Hill, in Warwickshire, where she died in 1658.

Her eldest son, Lord Digby, inherited the castle, and it is still in the family’s possession.