In 1643, when civil war broke out in England, she assumed control of Corfe Castle when John Bankes had been ordered by the king to serve in combat in London and Oxford. She remained behind with her children, servants, and a force of five men. By that point, Corfe Castle was the last Royalist garrison on the Dorsetshire coast. In May 1643, a force of Parliamentarians, consisting of forty seamen, demanded the surrender of the castle's four pieces of ordnance. She, her maidservants, and her small group of soldiers retaliated with cannon fire and drove them away. Later, she gave up the ordnance in order to have some time to resupply the castle.