 He took the covenant on 25 September following, and was one of the managers of the impeachment of William Laud in January–March 1643/4.With his friend Bulstrode Whitelocke, Maynard attended, by Essex's invitation, a meeting of the anti-Cromwellian faction, held at Essex House in December 1644, to discuss the expediency of taking public action against Cromwell as an 'incendiary.