The British Army has been a volunteer force since national service ended during the 1960s. Since the creation of the part-time, reserve Territorial Force in 1908 (renamed the Army Reserve in 2014), the full-time British Army has been known as the Regular Army. In July 2020 there were just over 78,800 Regulars, with a target strength of 82,000, and just over 30,000 Army Reservists, with a target strength of 30,000. All former Regular Army personnel may also be recalled to duty in exceptional circumstances during the 6-year period following completion of their Regular service, which creates an additional force known as the Regular Reserve.

The table below illustrates British Army personnel figures from 1710 to 2024.

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). The weapon was traditionally equipped with either iron sights or an optical SUSAT, although other optical sights have been subsequently purchased to supplement these. The weapon can be enhanced further utilising the Picatinny rail with attachments such as the L17A2 under-barrel grenade launcher. In 2023, the Army Special Operations Brigade, which includes the Ranger Regiment, began using the L403A1, an AR-pattern rifle also used by the Royal Marines.

Some soldiers are equipped with the 7.62mm L129A1 sharpshooter rifle, which in 2018 formally replaced the L86A2 Light Support Weapon. Support fire is provided by the L7 general-purpose machine gun (GPMG), and indirect fire is provided by L16 81mm mortars. Sniper rifles include the L118A1 7.62 mm, L115A3 and the AW50F, all manufactured by Accuracy International. The British Army utilises the Glock 17 as its side arm.

Anti tank guided weapons include the Javelin, the medium range anti-tank guided weapon replacement for Milan, with overfly and direct attack modes of operation, and the NLAW. The Next-generation Light Anti-tank Weapon (NLAW) is the first, non-expert, short-range, anti-tank missile that rapidly knocks out any main battle tank in just one shot by striking it from above.
The army's main battle tank is the Challenger 2, which is being upgraded to Challenger 3. It is supported by the Warrior tracked armoured vehicle as the primary infantry fighting vehicle, (which will soon be replaced by the Boxer 8x8 armoured fighting vehicle) and the Bulldog armoured personnel carrier. Light armoured units often utilise the Supacat "Jackal" MWMIK and Coyote tactical support vehicle for reconnaissance and fire support.
The army has three main artillery systems: the M270 multiple launch rocket system (MLRS), the AS-90 and the L118 light gun. The MLRS, first used in Operation Granby, has an 85-kilometre (53 mi) standard range, or with the PrSM, up to 500 km. The AS-90 is a 155 mm self-propelled armoured gun with a 24-kilometre (15 mi) range. The L118 light gun is a 105 mm towed gun, which is typically towed by a Pinzgauer all-terrain vehicle. To identify artillery targets, the army operates the TAIPAN artillery detection radar and utilises artillery sound ranging. For air defence it uses the new Sky Sabre system, which in 2021 replaced the Rapier. It also deploys the Very Short-Range Air Defence (VSHORAD) Starstreak HVM (high-velocity missile) launched by a single soldier or from a Stormer HVM vehicle-mounted launcher.

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Army Headquarters is located in Andover, Hampshire, and is responsible for providing forces at operational readiness for employment by the Permanent Joint Headquarters. The command structure is hierarchical, with overall command residing with the Chief of the General Staff (CGS), who is immediately subordinate to The Chief of Defence Staff, the head of the British Armed Services. The CGS is supported by the Deputy Chief of the General Staff. Army Headquarters is further organised into two subordinate commands, Field Army and Home Command, each commanded by a lieutenant general. 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. British Army units are either full-time 'Regular' units, or part-time Army Reserve units.
Led by a British Army three-star general, one of NATO's High Readiness (Land) Forces based in Gloucestershire, UK, with the following British units under its command:
• 1st Signal Brigade
• 104th Theatre Sustainment Brigade
• 7th Air Defence Group
• 8th Engineer Brigade
Led by Commander Field Army, the Field Army is responsible for generating and preparing forces for current and contingency operations. The Field Army comprises:
• 1st (United Kingdom) Division
• 3rd (United Kingdom) Division
• Field Army Troops
Home Command is the British Army's supporting command; a generating, recruiting and training force that supports the Field Army and delivers UK resilience. It comprises
• Army Personnel Centre, which deals with personnel issues and liaises with outside agencies.
• Army Personnel Services Group, which supports personnel administration
• Army Recruiting and Initial Training Command, which is responsible for all recruiting and training of Officers and Soldiers.
• London District Command, which is the main headquarters for all British Army units within the M25 corridor of London. It also provides for London's ceremonial events as well as supporting operational deployments overseas.
• Regional Command, which enables the delivery of a secure home front that sustains the Army, notably helping to coordinate the British Army's support to the civil authorities, overseeing the British Army's Welfare Service, and delivering the British Army's civil engagement mission.

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