Channel Islands in the Wars of the Three Kingdoms

Between 1642 and 1651 the Channel Islands were involved in an eleven-year-long, wide-scale armed conflict known as the English Civil War, between the Parliamentarians (nicknamed pejoratively as the Roundheads) and Royalists (nicknamed the Cavaliers) over, principally, the manner of England's government and the amount of power the monarch should be able to wield.

For the most part, Jersey remained loyal to the Crown (even sheltering the future Charles II of England on two separate occasions in 1646 and 1649), whereas Guernsey, with the exception of Castle Cornet, was under Parliamentarian control. By 1651, Parliament gained control of both the islands and held them during the Interregnum even imprisoning Leveller dissident John Lilburne in Mount Orgueil Castle on 16 March 1654, due to Jersey having no habeas corpus laws. After the restoration of monarchy in 1660, the Parliamentarian general John Lambert was imprisoned on Guernsey.