In 1641, the Great Irish Rebellion broke out. Lettice, by then a widow in her early sixties, became caught up in it at the end of 1641, when Lettice received a letter from her cousin, Henry O'Dempsey,
Viscount Clanmalier, containing fraudulent orders from King
Charles I to surrender Geashill Castle to the O'Dempseys, and leave with her people in a safe convoy provided by them. The letter continued with the threat to burn the castle and town, as well as to massacre all the
Protestant inhabitants, should she fail to yield to their demands. Lettice, who resided at the castle with her sons and some of her grandchildren, refused to hand over the castle, and sent a scornful letter back to Henry O'Dempsey:"I am, as I have ever been, a loyal subject of my king. I thank you for your offer of a convoy, which however, I hold as of little safety. Being free from offending His Majesty, or doing wrong to any of you, I will live and die innocently, and will do my best to defend my own, leaving the issue to God". In early 1642, the O'Dempseys made an assault on the castle, and more letters were exchanged, however, she and her people managed to hold out; she later refused to leave under the convoy of a relief party sent by
Dublin, preferring to defend her fortress. When the rebels had captured one of her sons, and brought him under the castle walls in chains, they threatened to decapitate him if she did not immediately surrender Geashill. Lettice retaliated by bringing one of her own prisoners, a
Catholic priest, onto the ramparts and threatened to kill him on the spot unless they released her son, unharmed. The rebels complied with her demand, and her son was returned to her. Well-armed with weapons and ammunition from Dublin, Lettice kept the insurgents at bay until October 1642 when Lettice was finally persuaded to leave Geashill in the company of
Sir Richard Grenville. She departed Ireland to retire to her late husband's family estate in Coleshill, England where she died in December 1658. She was buried alongside Sir Robert in Coleshill Parish Church. She was not succeeded by her eldest grandson, Kildare Digby (c.1627- 1661) as the patent of the barony of Offaly stipulated that upon her death the title was to pass to the head of the House of Kildare who in 1658 was
George FitzGerald, 16th Earl of Kildare. ==References==