They were a notoriously litigious couple, who spent many years asserting their rights before numerous courts, and were quite prepared to accuse even their closest relatives of wrongdoing.
[citation needed] In early 1642, around the age of about sixty-two, her castle of Geashill was besieged by a force of insurgents from the O'Dempsey clan; she managed to hold out against them until October 1642.
The marriage produced ten children:[4] Lettice and her husband were vigilant in asserting their legal rights, and they had a long-standing grievance over her exclusion from the Kildare inheritance.
By 1602, they had gathered a considerable body of evidence that her grandfather's purported deed, which settled the property on his male heirs only, might have been forged or tampered with by her grandmother Mabel, Dowager Countess of Kildare, who was still alive.
[6] Mabel admitted to altering the deed, but she put the entire blame on her barrister, Henry Burnell, who was censured for professional misconduct and fined.
At one point the Lord Deputy of Ireland, Sir Arthur Chichester, complained that for two entire law terms the Court of Castle Chamber had been unable to deal with any other business, due to its preoccupation with the Kildare case (which it should probably not have heard at all, since in theory Castle Chamber dealt only with cases involving public security).
[8] Lettice has been described as having been an accomplished negotiator,[9] and this skill paid off when finally, on 29 July 1620, after years of dispute, King James I granted her the suo jure title of 1st Baroness Offaly for life.
[11]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.
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.