In the summer of 1648, Parliamentarian troops in Wales, who faced long arrears in their pay, broke out in rebellion in support of the Royalist cause. The situation became more challenging when they were joined by local Royalist gentry and officers. Colonel Poyer, the Parliamentarian Govenor of Pembroke Castle, Colonel Powell, the equivalent at Tenby Castle, and Major-General Laugharne, became the leader of the revolt, leading the troops in an attack eastwards. Most of the rebel forces quickly surrendered, but at Pembroke, a strong defensive fortress, Oliver Cromwell was forced to undertake a serious siege. Cromwell eventually found the castle's weakness by cutting off its water supply, and Poyer finally gave in on 11 July.