British Army

The British Army is the principal land warfare force of the United Kingdom. As of 1 January 2025,^[update] the British Army comprises 73,847 regular full-time personnel, 4,127 Gurkhas, 25,742 volunteer reserve personnel and 4,697 "other personnel", for a total of 108,413.

The British Army traces back to 1707 and the formation of the united Kingdom of Great Britain which joined the Kingdoms of England and Scotland into a single state and, with that, united the English Army and the Scots Army as the British Army. The English Bill of Rights 1689 and Scottish Claim of Right Act 1689 require parliamentary consent for the Crown to maintain a peacetime standing army. Members of the British Army swear allegiance to the monarch as their commander-in-chief. The army is administered by the Ministry of Defence and commanded by the Chief of the General Staff.

At its inception, being composed primarily of cavalry and infantry, the British Army was one of two Regular Forces (there were also separate Reserve Forces) within the British military (those parts of the British Armed Forces tasked with land warfare, as opposed to the naval forces), with the other having been the Ordnance Military Corps (made up of the Royal Artillery, Royal Engineers, and the Royal Sappers and Miners) of the Board of Ordnance, which along with the originally civilian Commissariat Department, stores and supply departments, as well as barracks and other departments, were absorbed into the British Army when the Board of Ordnance was abolished in 1855. Various other civilian departments of the board were absorbed into the War Office.

The British Army has seen action in major wars between the world's great powers, including the Seven Years' War, the Napoleonic Wars, the Crimean War and the First and Second World Wars. Britain's victories in most of these decisive wars allowed it to influence world events and establish itself as one of the world's leading military and economic powers. Since the end of the Cold War, the British Army has been deployed to a number of conflict zones, often as part of an expeditionary force, a coalition force or part of a United Nations peacekeeping operation.

Until the Wars of the Three Kingdoms (1639–1653), neither England nor Scotland had a standing army with professional officers and career corporals and sergeants. England relied on militia organised by local officials or private forces mobilised by the nobility, or on hired mercenaries from Europe. From the later Middle Ages until the Wars of the Three Kingdoms, when a foreign expeditionary force was needed, such as the one that King Henry V took to France and that fought at the Battle of Agincourt (1415), the army, a professional one, was raised for the duration of the expedition.

During the Wars of the Three Kingdoms, the members of the English Long Parliament realised that the use of county militia organised into regional associations (such as the Eastern Association), often commanded by local members of Parliament (both from the House of Commons and the House of Lords), while more than able to hold their own in the regions which Parliamentarians ('Roundheads") controlled, were unlikely to win the war. So Parliament initiated two actions. The Self-denying Ordinance forbade members of Parliament (with the notable exception of Oliver Cromwell, then a member of parliament and future Lord Protector) from serving as officers in the Parliamentary armies. This created a distinction between the civilians in Parliament, who tended to be Presbyterian and conciliatory to the Royalists ("Cavaliers") in nature, and a corps of professional officers, who tended to be Independent (Congregational) in theology. The second action was legislation for the creation of a Parliamentary-funded army, commanded by Lord General Thomas Fairfax, which became known as the New Model Army (originally phrased "new-modelled Army").

While this proved to be a war-winning formula, the New Model Army, being organised and politically active, went on to dominate the politics of the Interregnum and by 1660 was widely disliked. The New Model Army was paid off and disbanded at the later Restoration of the monarchy in 1660 with the accession of King Charles II. For many decades the alleged excesses of the New Model Army under the Protectorate / Commonwealth under Oliver Cromwell were used as propaganda (and still feature in Irish folklore) and the Whig Party element recoiled from allowing a standing army to continue with the agreed-upon rights and privileges under the return of a king. The militia acts of 1661 and 1662 prevented local authorities from calling up militia and oppressing their own local opponents. Calling up the militia was possible only if the king and local elites agreed to do so.

King Charles II and his "Cavalier" / Royalist supporters favoured a new army under royal control, and immediately after the Restoration of 1660 to 1661 began working on its establishment. The first English Army regiments, including elements of the disbanded New Model Army, were formed between November 1660 and January 1661 and became a standing military force for England (financed by Parliament). The Royal Scots and Irish Armies were financed by the parliaments of Scotland and Ireland. Parliamentary control was established by the Bill of Rights 1689 and Claim of Right Act 1689, although the monarch continued to influence aspects of army administration until at least the end of the 19th century.