The Clarke Papers. Selections from the Papers of William Clarke, Secretary to the Council of the Army, 1647-1649, and to General Monck and the Commanders of the Army in Scotland, 1651-1660, ed. C.H. Firth (Camden Society, 1901). 4 vols. http://oll.libertyfund.org/titles/1983,
The Clarke Papers chronicle the debates which took place in the Army during the English Civil War over the relationship between Parliament and the Army.
The text is in the public domain.