 When, in 1647, he was commanded to disband his army and surrender Pembroke Castle, he refused to do so on the grounds that he was owed money.In April 1648 he was contacted by the Prince of Wales and, with the support of other local Parliamentary commanders, Rowland Laugharne and Rice Powell, he joined a Royalist rebellion, culminating in the Battle of St Fagans.The remaining forces, besieged by Oliver Cromwell himself at Pembroke, surrendered on 11 July 1648, and Poyer, Laugharne and Powell were condemned to death.