Editing British Armed Forces (section)

==History==
{{Main|History of the Royal Navy|History of the British Army|History of the Royal Air Force}}
[[File:Ourworldindata uk-defence-spending-as-a-percentage-of-gdp.png|thumb|Defence spending in the UK]]

===Organisation===
With the [[Acts of Union 1707]], the armed forces of England and Scotland were merged into the armed forces of the [[Kingdom of Great Britain]].<ref name=Union1707>[http://www.parliament.uk/about/living-heritage/evolutionofparliament/legislativescrutiny/ Acts of Union 1707] {{Webarchive|url=https://web.archive.org/web/20120529130147/http://www.parliament.uk/about/living-heritage/evolutionofparliament/legislativescrutiny/ |date=29 May 2012 }} parliament.uk, accessed 31 December 2010; [http://www.nationalarchives.gov.uk/pathways/citizenship/rise_parliament/uniting.htm Uniting the kingdom?] {{Webarchive|url=https://web.archive.org/web/20160308174527/http://www.nationalarchives.gov.uk/pathways/citizenship/rise_parliament/uniting.htm |date=8 March 2016 }} nationalarchives.gov.uk, accessed 31 December 2010; [http://www.scottish.parliament.uk/vli/visitingHolyrood/union_exhibition.pdf Making the Act of Union 1707] {{Webarchive|url=https://web.archive.org/web/20110511140052/http://www.scottish.parliament.uk/vli/visitingHolyrood/union_exhibition.pdf |date=11 May 2011 }} scottish.parliament.uk, accessed 31 December 2010</ref>

There were originally several naval and several military regular and reserve ''forces'', although most of these were consolidated into the Royal Navy or the British Army during the 19th and 20th Centuries (the [[Royal Naval Air Service]] and the [[Royal Flying Corps]] of the British Army, by contrast, were separated from their parent forces in 1918 and amalgamated to form a new force, the [[Royal Air Force]], which would have complete responsibility for naval, military and strategic aviation until the [[Second World War]]).

Naval forces included the [[Royal Navy]], the [[Waterguard]], later renamed the [[HM Coastguard]], and [[Sea Fencibles]] and ''River Fencibles'' formed as and when required for the duration of emergencies. The [[Merchant Navy]] and offshore fishing boat crews were also important manpower reserves to the armed naval forces. Any seaman was liable to [[impressment]], with many so conscripted especially during the two decades of conflict from the French Revolution until the end of the Napoleonic Wars, and from 1835 registered on the ''Register of Seamen'' to identify them as a potential resource, and many of their seamen would serve part time in the [[Royal Navy Reserve]], created under the Naval Reserve Act 1859, and [[Royal Naval Volunteer Reserve]], created in 1903.

The British military (those parts of the British Armed Forces tasked with land warfare, as opposed to the naval forces)<ref>{{citation |url=https://api.parliament.uk/historic-hansard/commons/1917/feb/12/naval-and-military-pensions-and-grants |title=NAVAL AND MILITARY PENSIONS AND GRANTS |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=12 February 1917 |volume=90 |at=cc248-51 |access-date=8 June 2021 |archive-date=21 May 2022 |archive-url=https://web.archive.org/web/20220521061200/http://hansard.millbanksystems.com/commons/1917/feb/12/naval-and-military-pensions-and-grants |url-status=live }}</ref> historically was divided into a number of [[Units of the British Army#Forces|military forces]], of which the British Army (also referred to historically as the 'Regular Army' and the 'Regular Force') was only one.<ref>''A LIST OF THE OFFICERS of the ARMY, (WITH AN ALPHABETICAL INDEX;) OF THE OFFICERS of the ROYAL ARTILLERY, THE ENGINEERS, the MARINE FORCES, AND OF THE OFFICERS on HALF-PAY; AND A SUCCESSION of COLONELS. THE THIRTY-SECOND EDITION''. War-Office. 31 March 1784</ref><ref>{{citation |title=THE NEW ANNUAL ARMY LIST, MILITIA LIST |date= 1854 <!--: (BEING THE FIFTEENTH ANNUAL VOLUME), CONTAINING THE DATES OF COMMISSIONS, AND A STATEMENT OF THE WAR SERVICES AND WOUNDS OF NEARLY EVERY OFFICER IN THE ARMY, ORDNANCE, AND MARINES. CORRECTED TO 30th December 1853 . WITH AN INDEX''. --> |author=Major H. G. Hart, 49TH REGT |publisher=John Murray |location=London}}</ref> The oldest of these organisations was the [[Militia (Great Britain)|Militia Force]] (also referred to as the ''Constitutional Force''),<ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/commons/1852/apr/23/militia-bill |title=''MILITIA BILL''. House of Commons Debate 23 April 1852. Volume 120 cc1035-109. British Parliament website |access-date=8 June 2021 |archive-date=24 May 2022 |archive-url=https://web.archive.org/web/20220524093720/http://hansard.millbanksystems.com/commons/1852/apr/23/militia-bill |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=23 April 1852 |url-status=live }}</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/commons/1855/may/04/the-militia |title=''THE MILITIA''. House of Commons Debate 4 May 1855. Volume 138 cc116-32. British Parliament website |access-date=8 June 2021 |archive-date=25 April 2022 |archive-url=https://web.archive.org/web/20220425093514/http://hansard.millbanksystems.com/commons/1855/may/04/the-militia |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=4 May 1855 |url-status=live }}</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/lords/1856/jul/11/the-militia-question |title=''THE MILITIA—QUESTION''. House of Lords Debate 11 July 1856. Volume 143 cc625-32. British Parliament website |access-date=8 June 2021 |archive-date=9 March 2017 |archive-url=https://web.archive.org/web/20170309065917/https://hansard.millbanksystems.com/lords/1856/jul/11/the-militia-question |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=11 July 1856 |url-status=live }}</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/commons/1878/jun/13/army-auxiliary-forces-the-militia |title=''ARMY—AUXILIARY FORCES—THE MILITIA.—OBSERVATIONS''. House of Commons Debate 13 June 1878. Volume 240 cc1418-33. British Parliament website |access-date=8 June 2021 |archive-date=23 May 2022 |archive-url=https://web.archive.org/web/20220523113730/http://hansard.millbanksystems.com/commons/1878/jun/13/army-auxiliary-forces-the-militia |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=13 June 1878 |url-status=live }}</ref> which (in the [[Kingdom of England]]) was originally the main military defensive force (there otherwise were originally only royal bodyguards, including the [[Yeomen Warders]] and the [[Yeomen of the Guard]], with armies raised only temporarily for expeditions overseas), made up of civilians embodied for annual training or emergencies, and had used various schemes of compulsory service during different periods of its long existence.

The Militia was originally an all infantry force, organised at the city or county level, and members were not required to serve outside of their recruitment area, although the area within which militia units in Britain could be posted was increased to anywhere in the Britain during the 18th century, and [[Militia Artillery units of the United Kingdom and Colonies|Militia coastal artillery]], field artillery, and engineers units were introduced from the 1850s.<ref name="norman1987">''The Militia Artillery 1852-1909'', by Norman EH Litchfield. The Sherwood Press (Nottingham) Ltd. 1987</ref> The [[Yeomanry]] was a mounted force that could be mobilised in times of war or emergency.<ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/lords/1903/may/26/an-imperial-yeomanry-reserve |title=''AN IMPERIAL YEOMANRY RESERVE''. House of Lords Debate 26 May 1903. Vol 122 cc1767-71. British Parliament website |access-date=8 June 2021 |archive-date=16 August 2021 |archive-url=https://web.archive.org/web/20210816133114/http://hansard.millbanksystems.com/lords/1903/may/26/an-imperial-yeomanry-reserve |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=26 May 1903 |url-status=live }}</ref> [[Volunteer Force]] units were also frequently raised during wartime, which did not rely on compulsory service and hence attracted recruits keen to avoid the Militia. These were seen as a useful way to add to military strength economically during wartime, but otherwise as a drain on the Militia and so were not normally maintained in peacetime, although in Bermuda prominent propertied men were still appointed ''Captains of Forts'', taking charge of maintaining and commanding fortified [[coastal artillery]] batteries and manned by volunteers (reinforced in wartime by embodied militiamen), defending the colony's coast from the 17th century to the 19th century (when all of the batteries were taken over by the regular Royal Artillery).<ref>''Bermuda Forts 1612–1957'', Dr. Edward Cecil Harris, The Bermuda Maritime Museum Press, {{ISBN|0-921560-11-7}}</ref><ref>''Bulwark Of Empire: Bermuda's Fortified Naval Base 1860–1920'', Lt.-Col. Roger Willock, USMC, The Bermuda Maritime Museum Press, The Bermuda Maritime Museum. {{ISBN|978-0-921560-00-5}}</ref> The militia system was extended to a number of English (subsequently ''British'') colonies, beginning with [[Colony of Virginia|Virginia]] and [[Bermuda]]. In some colonies, ''Troops of Horse'' or other mounted units similar to the Yeomanry were also created.<ref>{{Cite web |url=http://www.bermudastamps.co.uk/1988/11/10/military-uniforms-bermuda |title=''1988 Military Uniforms of Bermuda'', By Neil Rigby on November 10, 1988 in First Day Covers, Queen Elizabeth II. Bermuda Stamps website |access-date=8 June 2021 |archive-date=23 April 2021 |archive-url=https://web.archive.org/web/20210423020210/http://www.bermudastamps.co.uk/1988/11/10/military-uniforms-bermuda/ |url-status=dead }}</ref> The militia and volunteer units of a colony were generally considered to be separate forces from the ''Home'' Militia Force and Volunteer Force in the United Kingdom, and from the militia forces and volunteer forces of other colonies. Where a colony had more than one militia or volunteer unit, they would be grouped as a militia or volunteer force for that colony, such as the Jamaica Volunteer Defence Force, which comprised the St. Andrew Rifle Corps, or Kingston Infantry Volunteers, the Jamaica Corps of Scouts, and the Jamaica Reserve Regiment,<ref>[https://www.jdfweb.com/third-battalion-duties/ ''Jamaica Defence Force: Third Battalion Duties''. Jamaica Defence Force website]</ref> but not the [[Jamaica Militia Artillery]].<ref>{{Cite web |url=https://livelb.nationalarchives.gov.uk/first-world-war/a-global-view/the-caribbean/jamaica/ |title=''Jamaica in 1914: War effort'' The National Archives, Kew |access-date=8 June 2021 |archive-date=8 June 2021 |archive-url=https://web.archive.org/web/20210608121902/https://livelb.nationalarchives.gov.uk/first-world-war/a-global-view/the-caribbean/jamaica/ |url-status=dead }}</ref> In smaller colonies with a single militia or volunteer unit, that single unit would still be considered to be listed within a force, or in some case might be named a force rather than a regiment or corps, such as is the case for the [[Falkland Islands Defence Force]] and the [[Royal Montserrat Defence Force]]. The militia, yeomanry and volunteer forces collectively were known as the ''reserve forces'', ''auxiliary forces'', or ''local forces''. Officers of these forces could not sit on courts martial of regular forces personnel. The [[Mutiny Act]] did not apply to members of the Reserve Forces.

The other regular military force that existed alongside the British Army was the [[Board of Ordnance]], which included the ''Ordnance Military Corps'' (made up of the Royal Artillery, Royal Engineers, and the Royal Sappers and Miners), as well as the originally-civilian [[Commissariat#19th century|Commissariat Stores]] and transport departments, as well as barracks departments, ordnance factories and various other functions supporting the various naval and military forces.<ref>{{Cite web |url=https://www.forces-war-records.co.uk/units/3224/department-of-the-master-general-of-the-ordnance |title=''Unit History: Department of the Master-General of the Ordnance''. Forces War Records |access-date=8 June 2021 |archive-date=5 October 2021 |archive-url=https://web.archive.org/web/20211005123115/https://www.forces-war-records.co.uk/units/3224/department-of-the-master-general-of-the-ordnance |url-status=dead }}</ref><ref>{{usurped|1=[https://web.archive.org/web/20210511140506/https://www.navalhistoryarchive.org/index.php/Board_of_Ordnance ''Board of Ordnance''. Naval History Archive]}}</ref> The English Army, subsequently the British Army once Scottish regiments were moved onto its establishment following the Union of the Kingdoms of Scotland and England, was originally a separate force from these, but absorbed the Ordnance Military Corps and various previously civilian departments after the Board of Ordnance was abolished in 1855.<ref>{{cite journal | url=https://www.jstor.org/stable/44220102 | jstor=44220102 | title=The Honorable the Board of Ordnance. 1299—1855 | last1=Leslie | first1=J. H. | journal=Journal of the Society for Army Historical Research | date=1925 | volume=4 | issue=17 | pages=100–104 }}</ref><ref>[https://www.nam.ac.uk/explore/corps-royal-engineers ''Corps of Royal Engineers''. National Army Museum]</ref> The ''Reserve Forces'' (which referred to the Home Yeomanry, Militia and Volunteer Forces before the 1859 creation of the [[Regular Reserve (United Kingdom)#Army Reserve (Regular)|British Army ''Regular Reserve'']] by [[Secretary of State for War]] [[Sidney Herbert, 1st Baron Herbert of Lea|Sidney Herbert]], and re-organised under the [[Reserve Force Act 1867]])<ref>''The Army Book For The British Empire'', by Lieutenant-General WH Goodenough, Royal Artillery, CB, and Lieutenant-Colonel JC Dalton (HP), Royal Artillery, Her Majesty's Stationery Office, London. 1893.</ref> were increasingly integrated with the British Army through a succession of reforms over the last two decades of the 19th century (in 1871, command of the Auxiliary Forces in the British Isles was taken from the [[Lord-Lieutenant|Lords-Lieutenant of counties]] and transferred to the [[War Office]], though colonial governors retained control of their militia and volunteer forces, and by the end of the century, at the latest, any unit wholly or partly funded from Army funds was considered part of the British Army) and the early years of the 20th century,<ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/commons/1895/mar/15/the-army-estimates |title=''THE ARMY ESTIMATES''. House of Commons Debate 15 March 1895. Vol 31 cc1157-209. British Parliament website |access-date=8 June 2021 |archive-date=18 August 2021 |archive-url=https://web.archive.org/web/20210818023526/http://hansard.millbanksystems.com/commons/1895/mar/15/the-army-estimates |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=15 March 1895 |url-status=live }}</ref> whereby the Reserve Forces units mostly lost their own identities and became numbered [[Territorial Force]] sub-units of regular British Army corps or regiments (the Home Militia had followed this path, with the Militia Infantry units becoming numbered battalions of British Army regiments, and the Militia Artillery integrating within Royal Artillery territorial divisions in 1882 and 1889, and becoming parts of the [[Royal Field Artillery]] or [[Royal Garrison Artillery]] in 1902 (though retaining their traditional corps names), but was not merged into the Territorial Force when it was created in 1908 (by the merger of the Yeomanry and Volunteer Force). The Militia was instead renamed the ''Special Reserve'',<ref>''Hart's Annual Army List, Special Reserve List, and Territorial Force List, for 1911: (Being the Seventy-Second Annual Volume,) Containing Dates of Commissions, and a Summary of the War Services of Nearly Every Officer in the Army, Supply &c. Departments, Marines, and Indian Army, and Indian Local Forces. With an Index.'' By the late Lieutenant general H. G. Hart. John Murray, Albemarle Street, London. 1911</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/lords/1908/feb/18/the-territorial-forces-act-the-militia |title=''THE TERRITORIAL FORCES ACT—THE MILITIA''. House of Lords Debate 18 February 1908. Volume 184 cc578-605. British Parliament website |access-date=8 June 2021 |archive-date=8 March 2017 |archive-url=https://web.archive.org/web/20170308220253/https://hansard.millbanksystems.com/lords/1908/feb/18/the-territorial-forces-act-the-militia |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=18 February 1908 |url-status=live }}</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/written-answers/1913/apr/09/british-army-home-and-colonial-military |title=''BRITISH ARMY.—HOME AND COLONIAL MILITARY FORCES''. House of Commons Debate 9 April 1913. Volume 51 cc1196-8W. British Parliament website |access-date=8 June 2021 |archive-date=18 August 2021 |archive-url=https://web.archive.org/web/20210818113804/http://hansard.millbanksystems.com/written_answers/1913/apr/09/british-army-home-and-colonial-military |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=9 April 1913 |url-status=live }}</ref> and was permanently suspended after the First World War (although a handful of Militia units survived in the United Kingdom, its colonies, and the Crown Dependencies). Unlike the Home, Imperial Fortress and Crown Dependency Militia and Volunteer units and forces that continued to exist after the First World War, although parts of the British military, most were not considered parts of the [[British Army]]<ref>[https://www.stabroeknews.com/2008/10/01/guyana-review/the-british-guiana-volunteer-force ''The British Guiana Volunteer Force''. Stabroek News. 1 October, 2008]</ref><ref>{{Cite web |url=https://www.colonialforces.org/batteries-companies-regiments-and-c |title=''Batteries, Companies, Regiments and Corps (Land): Defending the colony'', Colonial Forces Study Group (Queensland) Inc |access-date=8 June 2021 |archive-date=27 January 2021 |archive-url=https://web.archive.org/web/20210127130254/https://www.colonialforces.org/batteries-companies-regiments-and-c |url-status=usurped }}</ref> unless they received Army funds, as was the case for the [[Bermuda Militia Artillery]] and the [[Bermuda Volunteer Rifle Corps]],<ref>''History of The Coast Artillery in the British Army'', by Colonel KW Maurice-Jones, DSO, RA. Royal Artillery Institution. 1959</ref><ref name="norman1987" /> which was generally only the case for those in the Channel Islands or the Imperial Fortress colonies (Nova Scotia, before [[Canadian confederation]], Bermuda, Gibraltar, and Malta).<ref>{{Cite web |url=https://livelb.nationalarchives.gov.uk/first-world-war/a-global-view/the-caribbean/bermuda |title=''Bermuda in 1914'' The National Archives, Kew |access-date=8 June 2021 |archive-date=17 June 2021 |archive-url=https://web.archive.org/web/20210617014624/https://livelb.nationalarchives.gov.uk/first-world-war/a-global-view/the-caribbean/bermuda/ |url-status=dead }}</ref><ref>''The Quarterly Army List''  Part I, January 1945. Order of Precedence of the British Army. Page xiii. His Majesty's Stationery Office</ref><ref>{{Cite web |url=https://api.parliament.uk/historic-hansard/commons/1899/mar/17/army-estimates-1899-1900#division_48 |title=''ARMY ESTIMATES, 1899–1900''. House of Commons Debate 17 March 1899. Vol 68 cc1161-287 British Parliament website |access-date=8 June 2021 |archive-date=16 August 2021 |archive-url=https://web.archive.org/web/20210816203541/http://hansard.millbanksystems.com/commons/1899/mar/17/army-estimates-1899-1900/division_48 |work=[[Hansard|Parliamentary Debates (Hansard)]] |date=17 March 1899 |url-status=live }}</ref> Today, the British Army is the only Home British military force (unless the [[Army Cadet Force]] and the [[Combined Cadet Force]] are considered), including both the regular army and the forces it absorbed, though British military units organised on Territorial lines remain in British Overseas Territories that are still not considered formally part of the British Army, with only the [[Royal Gibraltar Regiment]] and the [[Royal Bermuda Regiment]] (an amalgam of the old Bermuda Militia Artillery and Bermuda Volunteer Rifle Corps) appearing on the British Army order of precedence and in the Army List.

Confusingly, and similarly to the dual meaning of the word [[Corps#United Kingdom|Corps]] in the British Army. As an example, the 1st Battalion of the [[King's Royal Rifle Corps]] was in 1914 part of the 6th Brigade that was part of the [[2nd Infantry Division (United Kingdom)|2nd Infantry Division]], which was itself part of [[I Corps (United Kingdom)|1st Army Corps]]), the British Army sometimes also used the term [[Expeditionary warfare|expeditionary force]] or [[field force]] to describe a body made up of British Army units, most notably the [[British Expeditionary Force (World War I)|British Expeditionary Force]], or of a mixture of British Army, Indian Army, or Imperial auxiliary units, such as the [[Siege of Malakand#Malakand Field Force|Malakand Field Force]] (this is similarly to the naval use of the term [[task force]]). In this usage, ''force'' is used to describe a self-reliant body able to act without external support, at least within the parameters of the task or objective for which it is employed.

===British Empire===
[[File:Battle of Trafalgar Poster 1805.jpg|thumb|A modern reproduction of an 1805 poster commemorating the [[Battle of Trafalgar]]]]

During the later half of the 17th century, and in particular, throughout the 18th century, British foreign policy sought to contain the expansion of rival European powers through military, diplomatic and commercial means, especially of its chief competitors [[Spain]], the [[Netherlands]], and [[France]]. This saw Britain engage in a number of intense conflicts over colonial possessions and world trade, including a long string of Anglo-Spanish and Anglo-Dutch wars, as well as a series of "world wars" with France, such as; the [[Seven Years' War]] (1756–1763), the [[French Revolutionary Wars]] (1792–1802) and the [[Napoleonic Wars]] (1803–1815). During the Napoleonic wars, the Royal Navy victory at [[Battle of Trafalgar|Trafalgar]] (1805) under the command of [[Horatio Nelson, 1st Viscount Nelson|Horatio Nelson]] (aboard [[HMS Victory|HMS ''Victory'']]) marked the culmination of British maritime supremacy, and left the Navy in a position of uncontested hegemony at sea.<ref>Nelson's Navy: The Ships, Men, and Organization, 1793-1815Brian Lavery</ref> By 1815 and the conclusion of the Napoleonic Wars, Britain had risen to become the world's dominant [[great power]] and the [[British Empire]] subsequently presided over a period of relative peace, known as [[Pax Britannica]].<ref name=Johnston>{{cite book|last1=Johnston|first1=Douglas M.|last2=Reisman|first2=W. Michael|title=The Historical Foundations of World Order|date=2008|publisher=Martinus Nijhoff Publishers|location=Leiden|isbn=978-9047423935|url=https://books.google.com/books?id=dVuwCQAAQBAJ&pg=PA508|ref=refJohnston2008}}, pp.&nbsp;508–10.</ref><ref>[[Brison D. Gooch]], ''Recent Literature on Queen Victoria's Little Wars'' ''Victorian Studies,'' 17#2 (1973): 217-224 [https://www.jstor.org/stable/3826186 online].</ref>

With Britain's old rivals no-longer a threat, the 19th century saw the emergence of a new rival, the [[Russian Empire]], and a strategic competition in what became known as [[The Great Game]] for supremacy in [[Central Asia]].<ref name=keay419>{{cite book|last=Keay|first=John|title=India: A History|year=2010|publisher=Grove Press|location=New York, NY|isbn=978-0-8021-4558-1|edition=revised|author-link=John Keay|pages=418–9}}</ref> Britain feared that Russian expansionism in the region would eventually threaten the [[British Raj|Empire]] in India.<ref name=keay419/> In response, Britain undertook a number of pre-emptive actions against perceived Russian ambitions, including the [[First Anglo-Afghan War]] (1839–1842), the [[Second Anglo-Afghan War]] (1878–1880)<ref name=Schmidt>{{cite book|last=Schmidt|first=Karl J.|title=An Atlas and Survey of South Asian History|year=1995|publisher=M.E. Sharpe|isbn=978-1563243332|page=[https://archive.org/details/atlassurveyofsou0000schm/page/74 74]|url-access=registration|url=https://archive.org/details/atlassurveyofsou0000schm/page/74}}</ref> and the [[British expedition to Tibet]] (1903–1904). During this period, Britain also sought to maintain the [[Balance of power (international relations)|balance of power]] in Europe, particularly against Russian expansionism,<ref>{{cite journal | last1 = Hew Strachan | first1 = Hew | year = 1978 | title = Soldiers, Strategy and Sebastopol | journal = Historical Journal | volume = 21 | issue = 2| pages = 303–325 | doi=10.1017/s0018246x00000558 | jstor=2638262| s2cid = 154085359 }}</ref> who at the expense of the waning [[Ottoman Empire]] had ambitions to "carve up the European part of Turkey".<ref name=ALambert>{{cite web|last1=Lambert|first1=Andrew|title=The Crimean War|url=https://www.bbc.co.uk/history/british/victorians/crimea_01.shtml|website=The BBC - History|publisher=The BBC|access-date=21 January 2016|archive-url=https://web.archive.org/web/20151210171630/http://www.bbc.co.uk/history/british/victorians/crimea_01.shtml|archive-date=10 December 2015|url-status=live}}</ref> This ultimately led to British involvement in the [[Crimean War]] (1854–1856) against the Russian Empire.<ref name=ALambert/>

[[File:Royal Irish Rifles ration party Somme July 1916.jpg|thumb|[[Royal Irish Rifles]] soldiers at the [[Battle of the Somme]] in 1916]]

===First World War===
The beginning of the 20th century served to [[Anglo-Russian Entente|reduce tensions]] between Britain and the Russian Empire, partly due to the emergence of a unified [[German Empire]]. The era brought about an [[Anglo-German naval arms race]], which encouraged significant advancements in maritime technology, including [[Dreadnought]]s, [[torpedo]]es, [[submarine]]s), and, in 1906, Britain determined that its only likely naval enemy was Germany.<ref>Herwig p. 48–50</ref> The [[Causes of World War I|accumulated tensions]] in European relations finally broke out into the hostilities of the [[First World War]] (1914–1918), in what is recognised today, as the most devastating war in British military history, with nearly 800,000 men killed and over 2&nbsp;million wounded.<ref>{{citation |last=Willmott |first=H.P. |year=2003 |title=World War I |location=New York |publisher=Dorling Kindersley |isbn=978-0-7894-9627-0 |oclc=52541937}}</ref> [[Allies of World War I|Allied]] victory resulted in the defeat of the [[Central Powers]], the end of the German Empire, the [[Treaty of Versailles]] and the establishment of the [[League of Nations]].

===Second World War===
[[File:No. 4 Commando 22 April 1942.jpg|thumb|British commandos during the Second World War]]
Germany was defeated in the First World War, but by 1933 [[fascism]] had given rise to [[Nazi Germany]], which under the leadership of [[Adolf Hitler]] re-militarised in defiance of the Treaty of Versailles. Once again [[Causes of World War II|tensions accumulated]] in European relations, and following Germany's [[invasion of Poland]] in September 1939, the [[Second World War]] began (1939–1945).<ref>{{cite book|last=Mallinson |first=Allan |year=2009 |title=The Making of the British Army |publisher=Bantam Press |isbn=978-0-593-05108-5}}</ref> The conflict was the most widespread in British history, with British Empire and [[Commonwealth of Nations|Commonwealth]] troops engaged in military campaigns in Europe, [[North Africa]], the [[Middle East]], and the [[Far East]]. Approximately 390,000 British Empire and Commonwealth troops died.<ref>{{cite web|title=Commonwealth War Graves Commission Annual Report 2014–2015 p. 38|url=https://issuu.com/wargravescommission/docs/ar_2014-2015?e=4065448/31764375|website=Commonwealth War Graves Commission|access-date=1 July 2016|archive-url=https://web.archive.org/web/20160625000629/https://issuu.com/wargravescommission/docs/ar_2014-2015?e=4065448%2F31764375|archive-date=25 June 2016|url-status=live}}</ref> [[Allies of World War II|Allied]] victory resulted in the defeat of the [[Axis powers]] and the establishment of the [[United Nations]], replacing the League of nations.

===Cold War===
{{Main|Outline of the British Armed Forces at the end of the Cold War}}
[[File:Avro Vulcan Bomber RAF.JPEG|thumb|The [[Vulcan Bomber]] was the mainstay of Britain's airborne nuclear capability for much of the [[Cold War]].]]
Post–Second World War economic and political decline, as well as changing attitudes in British society and government, were reflected by the armed forces' contracting global role,<ref>Colman (2005), ''A 'Special Relationship'?: Harold Wilson, Lyndon B. Johnson, and Anglo-American Relations' at the Summit', 1964–68'', p77</ref><ref name="Focus on Euope">[http://www.raf.mod.uk/rafcms/mediafiles/F21E81DC_E902_D3CE_488720FE8488434D.pdf Focus on Europe] {{Webarchive|url=https://web.archive.org/web/20070222004546/http://www.raf.mod.uk/rafcms/mediafiles/F21E81DC_E902_D3CE_488720FE8488434D.pdf |date=22 February 2007 }}, raf.mod.uk</ref> and later epitomised by its political defeat during the [[Suez Crisis]] (1956).<ref>Johnman & Gorst (1997), ''The Suez Crisis'', p166</ref> Reflecting [[British Empire#Decolonisation and decline (1945–1997)|Britain's new role in the world]] and the escalation of the [[Cold War]] (1947–1991), the country became a founding member of the [[NATO]] military alliance in 1949. [[Defence Review]]s, such as those in [[1957 Defence White Paper|1957]] and [[1966 Defence White Paper|1966]], announced significant reductions in conventional forces,<ref>Lider (1985), ''British Military Thought After World War II'', p525</ref> the pursuement of a doctrine based on [[nuclear deterrence]],<ref>Lee (1996), ''Aspects of British Political History 1914–1995'', 273</ref><ref>Pierre (1972), ''Nuclear Politics: the British experience with an independent strategic force: 1939–1970'', p100</ref> and a permanent military withdrawal [[east of Suez]].<ref>Hack (2000), ''Defence and Decolonisation in South-East Asia: Britain, Malaya, Singapore, 1941–1968'', p285</ref><ref>Chandler & Beckett (2003), p345</ref> By the mid-1970s, the armed forces had reconfigured to focus on the responsibilities allocated to them by NATO.<ref name="Focus on Euope" /><ref name="Navy-45-2000">[http://www.royal-navy.mod.uk/server/show/nav.3867 Vanguard to Trident 1945–2000] {{webarchive|url=https://web.archive.org/web/20070310224429/http://www.royal-navy.mod.uk/server/show/nav.3867 |date=10 March 2007 }}, royal-navy.mod.uk</ref><ref name=autogenerated2>Kennedy (2004), ''British Naval Strategy East of Suez, 1900–2000: Influence and Actions'', p193</ref> The [[British Army of the Rhine]] and [[RAF Germany]] consequently represented the largest and most important overseas commitments that the armed forces had during this period,<ref>Chandler & Beckett (2003), p421</ref> while the Royal Navy developed an [[anti-submarine warfare]] specialisation, with a particular focus on countering [[Soviet Union|Soviet]] submarines in the Eastern Atlantic and [[North Sea]].<ref name="Navy-45-2000" />

While NATO obligations took increased prominence, Britain nonetheless found itself engaged in a number of low-intensity conflicts, including a spate of insurgencies against colonial occupation.<ref name="Insurgencies">Chandler & Beckett (2003), pp350–351</ref> However the [[Dhofar Rebellion]] (1962–1976) and [[The Troubles]] (1969–1998) emerged as the primary operational concerns of the armed forces.<ref name="Insurgencies"/> Perhaps the most important conflict during the Cold War, at least in the context of British defence policy, was the [[Falklands War]] (1982).<ref name="Gibran">{{cite book|last1=Gibran|first1=Daniel K.|title=The Falklands War : Britain versus the past in the South Atlantic|date=1998|publisher=McFarland|location=Jefferson, N.C.|isbn=978-0786404063|page=161}}</ref>

Since [[Cold War (1985–91)|the end of the Cold War]], an increasingly international role for the armed forces has been pursued, with re-structuring to deliver a greater focus on [[expeditionary warfare]] and [[power projection]].<ref name="Adrian"/> This entailed the armed forces often constituting a major component in [[peacekeeping]] and humanitarian missions under the auspices of the United Nations, NATO, and other multinational operations,<ref>Frantzen (2005), ''Nato And Peace Support Operations, 1991–1999: Policies And Doctrines'', p104</ref> including: peacekeeping responsibilities in the [[Balkans]] and [[Cyprus]], the 2000 [[Operation Palliser|intervention in Sierra Leone]] and participation in the UN-mandated [[Libyan no-fly zone|no-fly zone over Libya]] (2011). Post-[[September 11 attacks|9/11]], the armed forces became heavily committed to the [[War on Terror]] (2001–present), with lengthy campaigns in [[War in Afghanistan (2001–2021)|Afghanistan]] (2001–2021) and [[Iraq War|Iraq]] (2003–2009), and more recently as part of the [[Military intervention against ISIL]] (2014–present). Britain's military intervention against [[Islamic State of Iraq and the Levant|Islamic State]] was expanded following a parliamentary vote to launch a bombing campaign over [[Syria]]; an extension of the bombing campaign requested by the Iraqi government against the same group. In addition to the aerial campaign, the British Army has trained and supplied allies on the ground and the [[Special Air Service]], the [[Special Boat Service]], and the [[Special Reconnaissance Regiment]] (British special forces) has carried out various missions on the ground in both Syria and Iraq.

The armed forces have also been called upon to assist with national emergencies through the provisions of the [[military aid to the civil authorities]] (MACA) mechanism. This has seen the armed forces assist government departments and civil authorities responding to flooding, food shortages, wildfires, terrorist attacks and the [[COVID-19 pandemic in the United Kingdom|COVID-19 pandemic]];<ref>{{cite web |title=2015 to 2020 government policy: Military Aid to the Civil Authorities for activities in the UK |url=https://www.gov.uk/government/publications/2015-to-2020-government-policy-military-aid-to-the-civil-authorities-for-activities-in-the-uk/2015-to-2020-government-policy-military-aid-to-the-civil-authorities-for-activities-in-the-uk |website=GOV.UK |access-date=12 August 2021 |date=4 August 2016}}</ref> the armed forces' support to the latter falls under [[Operation Rescript]], described as the UK's "biggest ever homeland military operation in peacetime" by the Ministry of Defence.<ref name="peacetime">{{cite news |title=COVID Response Becomes Military's 'Biggest Homeland Operation In Peacetime' |url=https://www.forces.net/news/covid-response-militarys-biggest-homeland-operation-peacetime |access-date=11 January 2021 |work=[[BFBS]] |date=4 January 2021}}</ref>

Figures released by the Ministry of Defence on 31 March 2016 show that 7,185 British Armed Forces personnel have lost their lives in [[Military awards and decorations of the United Kingdom|medal earning]] theatres since the end of the Second World War.<ref name="Deaths">[https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/512070/20160331_UK_Armed_Forces_Operational_deaths_post_World_War_II.O.pdf UK Armed Forces Deaths: Operational deaths post World War II 3 September 1945 to 17 February 2016] {{Webarchive|url=https://web.archive.org/web/20160911093201/https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/512070/20160331_UK_Armed_Forces_Operational_deaths_post_World_War_II.O.pdf |date=11 September 2016 }}, Ministry of Defence, gov.uk, Published 31 March 2016</ref>