In 1641 he left for England, deputed by the colony to act as ambassador at the Court of Charles I, to endeavour to procure some mitigation of the excise and customs duties, which weighed heavily on the colonists. But on reaching England he found that the Crown and the Parliament were at variance, and he did not care to return to America and to his wife whom he had left there, but elected to be the stormy petrel of the rebellion, flying over the land, and, as Ludlow says, advising the people everywhere to take arms in the cause of the Parliament. He was appointed chaplain to a brigade of troops sent into Ireland against the rebels, and he had no hesitation in wielding the sword as well as the tongue, the latter to animate the soldiers, the former to extirpate the Baal-worshippers. Then he hastened to Holland, where he collected thirty thousand pounds for the relief of the Protestants of Ireland,[4] who had been plundered and burnt out of their homes by the rebels. When Peters had effected his various purposes in Ireland, he returned to England, and made his report of the condition of affairs there to Sir Thomas Fairfax and Cromwell. In 1643 he was appointed, or thrust himself forward, to minister to Chaloner on the scaffold, as that man had been condemned to death for participation in Waller's plot. So again in 1644 he was on the scaffold haranguing and praying for and at Sir John Hotham, who probably would have preferred to die in quiet. Peters was now engaged as chaplain to the Parliamentary forces, and especially as a conveyer of despatches, for all which he received liberal payment. He was with the Earl of Warwick at the taking of Lyme, and was despatched by that nobleman to London to give an account of the affair in Parliament. On another occasion he was entrusted with letters from Sir Thomas Fairfax relating to the capture of Bridgwater, on which occasion he was voted a sum of £100. In the same year, 1645, he was commissioned by Sir Thomas to report the taking of Bristol. In March of that year Hugh Peters was with the army in Cornwall, and harangued at Bodmin against the Crown and the Church, and exhorted all good men and true to adhere to the cause of the Parliament.