When civil war broke out in 1642 between King Charles I and Parliament, Pendennis and the south-west of England were held by the Royalists. The growing town of Falmouth was a strategically important part of their supply route to the Continent, while Carrick Roads formed a base for Royalist piracy in the English Channel. As the war turned in favour of the Parliamentarians, preparations were made for Prince Charles to shelter there over the winter of 1645–46, as part of which the surrounding fortifications were improved; in the event, Charles stayed in the castle only briefly in early 1646.