From 1649 to 1660 the Cromwellian army, which grew out of the New Model Army, was the dominant political institution in the country and the foundation for each successive government. It forced through the regicide, purged parliaments, dissolved them, restored them, summoned new legislative bodies, produced a written constitution, and briefly flirted with direct military rule under the major-generals. The army elevated Oliver Cromwell, its Lord General, to the position of Lord Protector, and then turned against his son, Richard, and demolished the Protectorate. In 1660 part of the army engineered the restoration of the monarchy. There is no other period in English history, either before or since the interregnum, when a standing army exercised so much power and influence on the politics and government of the country. Its adoption of a political role was initially defensive in terms of securing its due after the civil war in terms of pay and arrears. In the face of parliamentary hostility, that focus on material issues broadened to incorporate a defense of the army’s right to petition and defend its honor and then widened further with its conviction that, as the embodiment of the godly cause, it had a right and a duty to be involved in the settlement of the nation. But the army never felt comfortable with the messy business of politics, and it spent the 1650s trying to find a parliament with which it could coexist.
The character of the army inevitably changed during the 11 years of the English republic. Death, wounds, retirement, and political differences removed many senior officers, as well as reshaping much of the junior officer corps and the rank and file. The physical dispersion of the regiments after the conquests of Ireland and Scotland led to substantially different means of political engagement and intervention compared to the years 1647 and 1648, when much of the army was quartered close together within striking distance of London. But alongside these developments there were some fundamental features of the army that remained constant: it continued to be a heterogenous institution that accommodated a wide range of political and religious beliefs among its officer corps; its veneration of Oliver Cromwell never wavered, albeit with some exceptions during the Protectorate, and, in turn, he tolerated its diversity while ruling the army with tight control; and the clarion cry of army unity as the bulwark against “the common enemy” (the Royalists) endured as a potent emotion, even for those who opposed Cromwell’s Protectorate. In 1659 and 1660, after Cromwell’s death, the restored Rump Parliament, the assembly that the army had dissolved in 1653, twice purged the army’s officer corps as it imposed tests of political correctness and fealty on an institution that it deeply distrusted. The purges wrecked army unity and left the army in England incapable of resisting General George Monck when he brought about the restoration of the monarchy.