[20] From the later Middle Ages until the Wars of the Three Kingdoms, when a foreign expeditionary force was needed, such as the one that Henry V of England 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.

[24] 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.

After Protestant dual Monarchs William III, formerly William of the Dutch House of Orange, and his wife Mary II's joint accession to the throne after a short constitutional crisis with Parliament sending Mary's father, predecessor King James II, (who remained a Catholic) during his brief controversial reign, off the throne and into exile.

[32][33] By the time of the 1707 Acts of Union, many regiments of the English and Scottish armies were combined under one operational command and stationed in the Netherlands for the War of the Spanish Succession.

Although all the regiments were now part of the new British military establishment,[5] they remained under the old operational-command structure and retained much of the institutional ethos, customs and traditions of the standing armies created shortly after the Restoration of the Monarchy 47 years earlier.

In 1713, when a new board of general officers was convened to decide the rank of several regiments, the seniority of the Scots Greys was reassessed and based on their June 1685 entry into England.

Although Spain was the dominant global power during the previous two centuries and the chief threat to England's early trans-Atlantic colonial ambitions, its influence was now waning.

[38] British soldiers captured strategically important sites and territories, with the army involved in wars to secure the empire's borders, internal safety and support friendly governments and princes.

[52] Halifax, Nova Scotia and Bermuda were to become Imperial fortresses (although Bermuda, being safer from attack over water and impervious to attack overland, quickly became the most important in British North America), along with Malta and Gibraltar, providing bases in the eastern Atlantic Ocean and Mediterranean Sea for Royal Navy squadrons to control the oceans and trade routes, and heavily garrisoned by the British Army both for defence of the bases and to provide mobile military forces to work with the Navy in amphibious operations throughout their regions.

The war between the British and the First French Empire of Napoleon Bonaparte stretched around the world; at its peak in 1813, the regular army contained over 250,000 men.

A coalition of Anglo-Dutch and Prussian armies under the Duke of Wellington and Field Marshal von Blücher finally defeated Napoleon at Waterloo in 1815.

The cost of paying pensioners, and the obligation the government was under to continue to employ invalids as well as soldiers deemed by their commanding officers as detriments to their units were motivations to change this system.

Battalions posted on garrison duty overseas were allowed an increase on their normal peacetime establishment, which resulted in their having surplus men on their return to a Home station.

A century earlier it vied with Napoleonic France for global pre-eminence, and Hanoverian Britain's natural allies were the kingdoms and principalities of northern Germany.

By the middle of the 19th century, Britain and France were allies in preventing Russia's appropriation of the Ottoman Empire, although the fear of French invasion led shortly afterwards to the creation of the Volunteer Force.

In 1915 the army created the Mediterranean Expeditionary Force to invade the Ottoman Empire via Gallipoli, an unsuccessful attempt to capture Constantinople and secure a sea route to Russia.

[70] Trench warfare dominated Western Front strategy for most of the war, and the use of chemical weapons (disabling and poison gases) added to the devastation.

It then fought through Italy[74] and, with the help of American, Canadian, Australian, New Zealand, Indian and Free French forces,[75] was the principal organiser and participant in the D-Day invasion of Normandy on 6 June 1944; nearly half the Allied soldiers were British.

[109] In December 2012 Prime Minister David Cameron announced that the combat mission would end in 2014, and troop numbers gradually fell as the Afghan National Army took over the brunt of the fighting.

The British Army leads a multinational armoured battlegroup in Estonia under Operation Cabrit and contributes troops to another military battle group in Poland.

[123] As part of the NATO plans, Britain has committed a full mechanized infantry brigade to be on a high state of readiness to defend Estonia.

The British Army's basic weapon is the 5.56 mm L85A2 or L85A3 assault rifle, with some specialist personnel using the L22A2 carbine variant (pilots and some tank crew).

[169] Day-to-day utility work uses a series of support vehicles, including six-, nine- and fifteen-tonne MAN trucks, Oshkosh heavy-equipment transporters (HET), close-support tankers, quad bikes and ambulances.

[175] The army operates two unmanned aerial vehicles in a surveillance role: the small Lockheed Martin Desert Hawk III and the larger Thales Watchkeeper WK450, which will be retired from service in March 2025.

[192] These two Commands serve distinct purposes and are divided into a structure of divisions and brigades, which themselves consist of a complex mix of smaller units such as Battalions.

[217] Since 2018 the British Army has been an equal-opportunity employer (with some legal exceptions due to medical standards), and does not discriminate based on race, religion or sexual orientation.

However, the Household Cavalry call many ranks by different names, the Royal Artillery refer to Corporals as Bombardiers, the Rifles spell Sergeant as Serjeant,[229] and Private soldiers are known by a wide variety of titles; notably trooper, gunner, guardsman, kingsman, sapper, signaller, fusilier, craftsman and rifleman dependant on the Regiment they belong to.

It differed from the Militia in a number of ways, most particularly in that volunteers did not commit to a term service, and were able to resign with fourteen days notice (except while embodied).

As with the Volunteers, members of the Yeomanry were expected to foot much of the cost of their own equipment, including their horses, and the make-up of the units tended to be from more affluent classes.

[263] The army has introduced tactical recognition flashes (TRFs); worn on the right arm of a combat uniform, the insignia denotes the wearer's regiment or corps.