The Second Civil War (1648) began in south Wales. The present study is the first detailed contextual narrative and analysis of the revolt in Wales, covering the originating mutiny at Pembroke Castle, its development into a rebellion that spread through south Wales, the Battle of St. Fagans (the biggest battle ever fought in Wales), and Cromwell's successful Welsh campaign involving the sieges of Chepstow, Tenby and Pembroke. The consequences of the revolt, involving the emergence of new local ruling elites and the cementing of a closer relationship with London central government, are...