It differed from other armies employed in the 1639 to 1653 Wars of the Three Kingdoms in that members were liable for service anywhere in the country, rather than being limited to a single area or garrison.

[2] When the First English Civil War began in August 1642, many of the largest militia were based in Parliamentarian areas like London, while Royalist counties like Shropshire or Glamorgan had fewer than 500 men.

[5][6] The review coincided with increasing dissatisfaction as to the conduct of certain senior commanders; in July 1644, a Parliamentarian force under Sir Thomas Fairfax and Oliver Cromwell secured control of Northern England by victory at Marston Moor.

The two commanders involved, Essex and Manchester, were accused by many in Parliament of lacking commitment, a group that included moderates like Sir William Waller as well as radicals like Cromwell.

[7] In December 1644, Sir Henry Vane introduced the Self-denying Ordinance, requiring those holding military commissions to resign from Parliament.

As members of the House of Lords, Manchester and Essex were automatically removed, since unlike MPs they could not resign their titles, although they could be re-appointed, 'if Parliament approved.

Since Cromwell was MP for Cambridge, command of the cavalry was initially given to Colonel Bartholomew Vermuyden, a former officer in the Eastern Association who was of Dutch origin and wanted to return home.

[9] Fairfax asked that Cromwell be appointed Lieutenant General of the Horse in place of Vermuyden, making him one of two original exceptions to the Self-denying Ordinance, the other being Sir William Brereton, commander in Cheshire.

Originally each regiment of cavalry had a company of dragoons attached, but at the urging of Fairfax on 1 March they were formed into a separate unit commanded by Colonel John Okey.

Fairfax had more than double the number of officers available for his 200 vacancies and those deemed surplus to requirements were either discharged or persuaded to re-enlist at a lower rank.

[1] On 9 June 1645, Sir Samuel Luke, one of the officers discharged, wrote the Army was "the bravest for bodies of men, horse and arms so far as the common soldiers as ever I saw in my life".

It is generally agreed that Fairfax, himself a moderate Presbyterian, sought to achieve a balance, while Essex and Manchester tried to remove those they viewed as unsuitable.

[20] The Oxford English Dictionary dated the earliest use of the phrase "New Model Army" to the works of the Scottish historian Thomas Carlyle in 1845, and the exact term does not appear in 17th- or 18th-century documents.

They wore a back-and-front breastplate over a buff leather coat, which itself gave some protection against sword cuts, and normally a lobster-tailed pot helmet with a movable three-barred visor.

It appears that after that date, unregimented companies of dragoons raised from the Militia and other sources were attached to the regiments of horse and foot as required.

[a] Pikemen, when fully equipped, wore a pot helmet, back- and breastplates over a buff coat, and often also armoured tassets to protect the upper legs.

[41] The establishment of the New Model also included at least two companies of "firelocks" or fusiliers, who wore "tawny coats" instead of red,[42] commanded initially by Major John Desborough.

Cromwell and the other commanders of the Army were not trained in siege warfare and generally tried to take fortified towns by storm rather than go through the complex and time-consuming process of building earthworks and trenches around it so that batteries of cannon could be brought close to the walls to pound it into surrender.

The Army generally performed well when storming fortifications, for example at the siege of Drogheda, but paid a heavy price at Clonmel when Cromwell ordered them to attack a well-defended breach.

Leaving the Scots and locally raised forces to contain the King, Fairfax marched into the West Country, where they destroyed the remaining Royalist field army at Langport on 10 July.

[47] Having come into contact with ideas from the radical movement called the Levellers, the troops of the Army proposed a revolutionary new constitution named the Agreement of the People, which called for almost universal male suffrage, electoral boundary reform, power to rest with a Parliament elected by the people every two years, religious freedom, and an end to imprisonment for debt.

[48] Increasingly concerned at the failure to pay their wages and by political manoeuvrings by King Charles I and by some in Parliament, the army marched slowly towards London over the next few months.

The New Model Army routed English royalist insurrections in Surrey and Kent, and in Wales, before crushing a Scottish invasion force at the Battle of Preston in August.

The majority of the Grandees realised that they could neither negotiate a settlement with Charles I, nor trust him to refrain from raising another army to attack them, so they came reluctantly to the same conclusion as the radicals: they would have to execute him.

The first involved 300 infantrymen of Colonel John Hewson's regiment, who declared that they would not serve in Ireland until the Levellers' programme had been realised.

After the resolution of the pay issue, the Banbury mutineers, consisting of 400 soldiers with Leveller sympathies under the command of Captain William Thompson, continued to negotiate for their political demands.

Cromwell launched a night attack on 13 May, in which several mutineers perished, but Captain Thompson escaped, only to be killed in another skirmish near the Diggers community at Wellingborough.

[59] The Army generally performed well when storming fortifications, for example at the siege of Drogheda, but paid a heavy price at Clonmel when Cromwell ordered them to attack a well-defended breach.

[43] In 1650, while the campaign in Ireland was still continuing, part of the New Model Army was transferred to Scotland to fight Scottish Covenanters at the start of the Third English Civil War.

In 1654, the English Commonwealth declared war on Spain, and regiments of the New Model Army were sent to conquer the Spanish colony of Hispaniola in the Caribbean.