Believing himself essential to any peace settlement, Charles had refused to compromise in negotiations; in December 1647 he made an agreement with representatives of the Scottish Parliament to restore him fully to the English throne in return for imposing a Presbyterian polity for three years.

Most Royalists had sworn at the end of the first war not to bear arms against Parliament and did not participate, one exception being Sir Nicholas Kemeys, who held Chepstow Castle for the king.

[6] At the beginning of May, Sir John Owen, a Caernarfonshire landowner who had served as Royalist governor of Conwy Castle during the first war, began recruiting in Merioneth.

Thomas Mytton, governor of Caernarfon and senior Parliamentarian commander in the area, was anxious to crush the rising before it grew further and sent an urgent message to Twisleton at Denbigh requesting reinforcement.

[10] Twisleton and John Carter, governor of Conwy, gathered a scratch force of less than 200 men from Chester and their own garrisons and set out to relieve Mytton, dragging two small field guns with them.

[11] Leaving a small number of men to blockade Mytton, he raised the siege and marched north-eastwards through Bangor: the wounded Lloyd died during the journey, allegedly of "neglect and ill-usage".

[13] The fighting was marked with some confusion: the commanders had chosen similar "field-words" ("Resolution" for Owen, and "Religion" for Twisleton) and the same "field-sign", in that neither side wore scarfs or sashes.

[16] Later in the month two of Owen's officers, Major John Dolben and Captain Charles Chambres, mounted another attempt: the diarist William Maurice wrote "aboute the 16th Dolbein and Chambers with their companye came before Denbigh castle, and in a bravado, discharged their pistols and wente away".

[13] While a number of North Wales Royalists remained in arms, Owen's defeat at Y Dalar Hir meant that the rebellion became largely confined to Anglesey.

The Scots invasion was defeated in August at Preston; in September it was reported that Byron had departed Anglesey for Dublin, and at the end of the month Mytton and a mixed force of 1,500 crossed the Menai Straits to restore order.