During her husband's absence in 1645, she took command of Fort La Tour at the mouth of the St John River when d'Aulnay attacked. Despite her stout defence over 3 days, her outnumbered forces were defeated. Mme La Tour surrendered on d'Aulnay's assurance of giving "quarter to all." However, he went back on his word and forced Mme La Tour to watch, a rope around her neck, as the garrison was hanged. She died 3 weeks later.