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.
Peters had uniformly, since he had been in the Low Countries, postured as an Independent hot and strong. Hitherto the Presbyterians had the prevailing party in Parliament, and among the discontents in the country, but now the Independents began to assert themselves and assume predominance. Their numbers were greatly increased by the return of the more fiery spirits who had, like Peters, abandoned England during the supremacy of Laud. Many of these, coming back from New England, had carried the doctrines of Puritanism to the very verge of extravagance, and not the least fiery and extravagant of these was Hugh Peters. These men rejected all ecclesiastical establishments, would admit of no spiritual authority in one man above another, and allowed of no interposition of the magistrate in religious matters. Each congregation, voluntarily united, was an integral and independent church, to exercise its own jurisdiction. The political system of the Independents was one of pure republicanism. They aspired to a total abolition of monarchy, even of the aristocracy, and projected a commonwealth in which all men should be equal. Sir Harry Vane, Oliver Cromwell, Nathaniel Fiennes, and Oliver St. John, the Solicitor-General, were regarded as their leaders, and Hugh Peters as their prophet.
Peters brought the news to Parliament of the capture of Winchester Castle, for which service he was paid £50. When Dartmouth was taken, he hastened thence to London, laden with crucifixes, vestments, papers, and sundry church ornaments, of which he had despoiled the beautiful church of S. Saviour's; and received in recompense from the Parliament an estate of which the House had deprived Lord Craven.
When the city of Worcester was besieged in the year 1646 by the Parliamentary forces, the governor consented to surrender on condition that passes were given to the soldiers and to the principal inhabitants. Peters negotiated the surrender.