Cornet George Joyce and New Model Army troops removed Charles I from parliamentary custody at Holdenby House in Northamptonshire on 3 June 1647. The army feared Parliament might disband it without satisfying arrears or political grievances. Possession of the king made the army an independent national political force.

Army declarations and pamphlets now addressed the nation in a collective military voice. Soldiers who had fought as Parliament's servants increasingly wrote as citizens claiming rights of conscience, pay and political participation.