"Friend, thou shouldest have invited all the Christians upon earth in all Nations that are against popery to thee, to come in and joyn with thee against popery, for thou hast had authority, stand to it, loose it not, nor abuse it, nor let any other take thy Crown, and do not stand cumbering thy self about dirty Priests that flatter thee for means, for thou hast had fair warnings, and thou hast had power over Nations, for Nations begins to be upon heaps, and Nations and tongues, and multitudes are waters, and the beast hath power over them who hath long reigned, and they begin to swell, and the whore sits upon them; neverthelesse, do not thou heed nor fear them, nor be of a doubtful mind, neither fear their amazements, but let thy heart be single to God, and wait, that the seed of God in thee may come until the top stone be layed, and invite all them that professe against the Pope in all Nations to joyn with thee against him, and do not loose thy Dominion nor authority, nor the wisdom of God, but with that thou may order all, that will keep thee single in heart and mind to the Lord, and let thy souldiers go forth with a free willing heart, that thou may rock Nations as a cradle, and keep thou in the fear of the Lord, and all thy souldiers, and them that be under thee, this is a charge to thee in the presence of the Lord God, that thou nor them may lose the dread of the Lord, for that is it that strikes terror in the hearts of all people. . . ."
George Fox to Oliver Cromwell, in a letter "Written the tenth of the 6th month, 1657". Edward Burrough and George Fox, Good counsel and advice rejected by disobedient men and the dayes of Oliver Cromwells visitation passed over, and also of Richard Cromwel his son . . . (London: Thomas Simmons, 1659), 36-37, all underscoring mine. The title of this post is taken from Alan Cole, "The Quakers and the English Revolution," in Crisis in Europe, 1560-1660, ed. Trevor Aston (New York: Basic Books, 1965), 349, who claims that it was not until the famous Declaration of January of 1661 (Declaration from the harmless & innocent people of God, called Quakers, against all sedition, plotters & fighters in the world . . . presented unto the king, upon the 21th day of the 11th moneth, 1660) that the movement became, in response to the new political situation, recognizably pacifist. The letter on pp. 26-27 is cited as well, but it doesn't seem to me to be as unambiguous. See, more importantly, the scan of the original in Google Books. I have no idea where the scholarship is on this topic (or its mid-17th-century context) at present.