Since his troops were not part of the New Model, Mytton retained his position. In December, he was appointed Vice-admiral of North Wales in place of Thomas Glynn and granted £5,000 of confiscated Royalist estates. The Second English Civil War began in April 1648 when unpaid Parliamentarian garrisons in South Wales defected but Mytton remained loyal. The revolt in the south was quickly suppressed, that in the north collapsed after he and Myddelton defeated a Royalist force at Red Hill on 1 October and recaptured Beaumaris Castle.