The Volunteer Force was a citizen army of part-time rifle, artillery and engineer corps, created as a popular movement throughout the British Empire in 1859. Originally highly autonomous, the units of volunteers became increasingly integrated with the British Army after the Childers Reforms in 1881, before forming part of the Territorial Force in 1908. Most of the regiments of the present Army Reserves Infantry, Artillery, Engineers and Signals units are directly descended from Volunteer Force units.

Prior to the Crimean War, the British military (i.e., land forces) was made up of multiple separate forces, with a basic division into the Regular Forces (including the British Army, composed primarily of cavalry and infantry, and the Ordnance Military Corps of the Board of Ordnance, made up of the Royal Artillery, Royal Engineers, and the Royal Sappers and Miners though not including the originally civilian Commissariat Department, stores and supply departments, all of which, with barracks and other departments, were absorbed into the British Army when the Board of Ordnance was abolished in 1855). and the Reserve Forces. After the 1855 consolidation of the Regular Forces (ignoring minor forces such as the Yeomen Warders and the Yeomen of the Guard) into the Regular Force (i.e., the British Army), there still remained a number of British military (not to be confused with naval) forces that were not part of the British Army; specifically the part-time Reserve Forces, which had at various times included the Honourable Artillery Company, Militia Force (also referred to as the Constitutional Force, and originally an infantry force), the Yeomanry Force (made up of mounted units, organised similarly to the Volunteer Force), Volunteer Force, and Fencibles. Equivalents were also raised in the Crown Dependencies and many colonies. Known collectively as the Reserve Forces, most of these had been allowed to lapse after the Napoleonic Wars, although the Yeomanry was maintained to potentially support the civil authorities against civil unrest, as at the 1819 Peterloo massacre, the Militia remained as a paper tiger, and rifle clubs were encouraged as the backbone against which the Volunteer force might be re-raised. The Militia and Volunteer Force were both re-organised in the 1850s. These forces were originally local-service, embodied during wartime or emergency, and placed under the control of Lords-Lieutenant of counties, and, in British colonies, under the colonial governors. After the British Army's Regular Reserve was created in 1859, by Secretary of State for War Sidney Herbert, and re-organised under the Reserve Force Act 1867 (30 & 31 Vict. c. 110), the Reserve forces, to avoid confusion, were generally known as the Auxiliary Forces or Local Forces. The Regulation of the Forces Act 1871 removed the Lord-Lieutenant as head of the county reserve forces and they were increasingly integrated with the British Army.

A large number of Volunteer Corps were formed during the French Revolutionary War but were stood down afterwards. Following the Crimean War, it was painfully clear to the War Office that, with half of the British Army dispositioned around the Empire on garrison duty, it had insufficient forces available to quickly compose and despatch an effective expeditionary force to a new area of conflict, unless it was to reduce the British Isles' own defences. During the Crimean War, the War Office had been forced to send militia and yeomanry to make up the shortfall of soldiers in the Regular Army. The situation had been complicated by the fact that both auxiliary forces were under the control of the Home Office until 1855.

Tensions rose between the United Kingdom and France following the Orsini affair, an assassination attempt on Emperor Napoleon III on 14 January 1858. It emerged that the would-be assassin, Felice Orsini had travelled to England to have the bombs used in the attack manufactured in Birmingham. The perceived threat of invasion by the much larger French Army was such that, even without sending a third of the army to another Crimea, Britain's military defences had already been stretched invitingly thin. On 29 April 1859 war broke out between France and the Austrian Empire (the Second Italian War of Independence), and there were fears that Britain might be caught up in a wider European conflict.

On 12 May 1859, the Secretary of State for War, Jonathan Peel issued a circular letter to lieutenants of counties in England, Wales and Scotland, authorising the formation of volunteer rifle corps (VRC, a.k.a. corps of rifle volunteers and rifle volunteer corps), and of artillery corps in defended coastal towns. Volunteer corps were to be raised under the provisions of the Volunteer Act 1804 (44 Geo. 3. c. 54), which had been used to form local defence forces during the Napoleonic Wars. Alfred Tennyson captured the spirit of the time by publishing his poem Riflemen Form in The Times on 9 May 1859. As a basis for the units, many communities had rifle clubs for the enjoyment of the sport of shooting.

Originally corps were to consist of approximately 100 all ranks under the command of a captain, with some localities having subdivisions of thirty men under a lieutenant. The purpose of the rifle corps was to harass the invading enemy's flanks, while artillery corps were to man coastal guns and forts. Although not mentioned in the circular letter, engineer corps were also formed, principally to place underwater mines for port defence. Stretcher-bearers attached to the rifle corps subsequently formed volunteer medical detachments affiliated to the Army Medical Corps. In a handful of counties, units of light horse or mounted rifles were formed.

Two volunteer units whose services had been accepted by Queen Victoria during the early 1850s became the two senior rifle corps of the new force. These were the Exeter and South Devon Volunteers, formed in 1852, who became the 1st Devonshire Rifle Volunteers (and were often referred to as the 1st Rifle Volunteer Corps), and the Victoria Rifles (descended from the Duke of Cumberland's Sharpshooters, formed in 1803) who became the 1st Middlesex Rifle Volunteers. An order of precedence was established for ninety-two other counties, depending upon the date of establishment of the first corps in the county.

The most senior artillery corps was the 1st Northumberland formed at Tynemouth on 2 August 1859.