In time of war, Cromwell appreciated that power lay with the army.
His political and military strategy was to carve out the old guard from any positions of power and remodel the army along more efficient grounds to exclude the weak-willed and the hapless. In December 1644, an increasingly militant Commons passed the Self-Denying Ordinance which excluded all MPs and Peers from command of the army (yet did not exclude Cromwell himself).
The move had the dual benefit of ridding the army of Manchester, Essex and the old guard as well as under-cutting the local basis of military organisation. With peers acting as regional commanders directing their local militia, the Parliamentary army had been disparate and ill-disciplined. In its place emerged a New Model Army under the command of Sir Thomas Fairfax - hero of Marston Moor and commander of Parliamentary forces in the North.
In early 1645, New Model Army strength stood at 22,000 men in eleven regiments of horse, twelve regiments of foot and ten companies of dragoons.
Freed from local interests and a regional base, the New Model Army was more flexible, mobile and deadly. Its social composition led opponents to dismiss it as a Territorial Army of part- timers and amateurs. One Presbyterian MP remarked how, 'most of the colonels are tradesmen, brewers, tailors, goldsmiths, shoemakers and the like.' But the Army signalled a reborn determination to bring the war to a conclusion. Fairfax's commission, unlike the original commander of the Parliamentary forces the Earl of Essex, did not contain a clause for the defence of the King's person. The Roundheads were now after Charles Stuart himself - not his evil advisers. After initial hesitance, Parliament was more clearly defining its aims.
After the chaotic plundering and charging of the early years, the New Model Army was to be professional and disciplined. No looting, no random violence, no blasphemy. They styled themselves as God's tool to rid Britain of popery - the original Christian Soldiers; crusaders for a New Jerusalem. The New Model Army would prove itself to be efficient, well-trained and committed. Like any religiously inspired revolutionary force, the New Model Army's strength lay in its certainty of purpose, and the fact that it was going to be paid regularly.