 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.