British Army First World War reserve brigades
The article lists British Army reserve brigades in World War I. At the start of the war volunteers in the vast majority of cases joined their local infantry regiment's reserve battalion. As the army expanded rapidly, further reserve battalions and brigades were formed. After conscription was introduced in 1916 the existing regimental system could not cope with the large influx of recruits and the existing reserve brigades were incorporated into the Training Reserve, with an official complement of over 209,000 soldiers, in addition to the regimental training units.
Recruitment
On 6 August 1914, less than 48 hours after Britain's declaration of war, Parliament sanctioned an increase of 500,000 men for the Regular British Army, and the newly-appointed Secretary of State for War, Earl Kitchener of Khartoum issued his famous call to arms: 'Your King and Country Need You', urging the first 100,000 volunteers to come forward. This group of six divisions with supporting arms became known as Kitchener's First New Army, or 'K1'. 'K2' and 'K3', followed shortly afterwards. In addition, recruits flooded into the drill halls of the part-time Territorial Force, which had largely volunteered for overseas service. The flood of volunteers overwhelmed the ability of the army to absorb and organise them, and by the time the Fifth New Army was authorised on 10 December 1914, many of the units were being organised as 'Pals battalions' under the auspices of mayors and corporations of towns up and down the country. Many of these pals who had lived and worked together, joined up and trained together and were allocated to the same units. The policy of drawing recruits from amongst the local population ensured that, when the Pals battalions suffered casualties, whole towns, villages, neighbourhoods and communities back in Britain were to suffer disproportionate losses.By the end of August 1914, 300,000 men had signed up to fight, and another 450,000 had joined up by the end of September. Voluntary recruitment remained fairly steady through 1914 and early 1915, but it fell dramatically thereafter. Conscription for single men was introduced in January 1916. Four months later, in May 1916, it was extended to all men aged 18 to 41. The Military Service Act March 1916 specified that men from the ages of 18 to 41 were liable to be called up for service in the army, unless they were married, or served in one of a number of reserved occupations, which were usually industrial but which also included clergymen and teachers. This legislation did not apply to Ireland, despite its then status as part of the United Kingdom. By January 1916, when conscription was introduced, 2.6 million men had volunteered for service, a further 2.3 million were conscripted before the end of the war; by the end of 1918, the army had reached its peak strength of 4 million men.
Training
Before the war British Army infantry regiments trained their recruits at their home depots from where they were drafted to one of their regiment's Regular Army battalions. On the outbreak of the war the part-time Special Reserve battalions were mobilised to supply these reinforcement drafts from Reservists, Special Reservists, returning wounded, and new recruits. The voluntary TF was also mobilised, and after its units volunteered for overseas service in August 1914 they began forming 2nd Line battalions to train their own recruits. By May 1915 the 2nd Line was also being prepared for overseas service, and the TF began forming 3rd Line units for training. Meanwhile, the battalions of the 1st, 2nd and 3rd New Armies were quickly formed at the regimental depots. The SR battalions also swelled with new recruits and were soon well above their establishment strength. By the autumn the depots were overwhelmed, and on 8 October 1914 each SR battalion at its coast defence station was ordered to use its surplus to form a service battalion of the 4th New Army. These were organised into six new divisions divided into 18 brigades. However, on 10 April 1915 the War Office decided to convert the K4 battalions into reserve units, to provide drafts for the K1–K3 battalions in the same way that the SR was doing for the Regular battalions. The K4 divisions were scrapped and their brigades renumbered as 1st–18th Reserve Brigades. Later the depot companies of the K5 battalions were combined into reserve battalions, and grouped into 19th–26th Reserve Brigades.On 1 September 1916 the whole training system was centralised with the formation of the Training Reserve. The K4 and K5 reserve battalions lost their regimental affiliation and were redesignated as 1st–112th TR battalions, to which all recruits not required for the regimental reserves were posted. They were issued with 'General Service' badges and could be drafted to any regiment, but the training officers and non-commissioned officers remained part of their parent regiments. The reserve brigades had now been concentrated at large training camps, and the TR had a total establishment of 209,537 men. Reserve brigades for the Machine Gun Corps were introduced in 1918. There was no change to the status or organisation of the SR battalions, but on 1 September 1916, the 3rd Line TF battalions were amalgamated into only one, two or at most three per infantry regiment, and grouped into new reserve brigades bearing the titles of the TF divisions they were reinforcing.
The scheme was further developed to provide for the progressive training of recruits under 19 years old. Of the 112 TR battalions, 42 were selected: 14 became 'Young Soldier Battalions' and 28 became 'Graduated Battalions'. When a recruit had finished initial training in the Young Soldier Battalion he was sent to one of two associated Graduated battalions, in which the four companies were organised by age, for training in 3-monthly steps between 18 and 19 years. As a result, every 3 months, 28 companies of newly trained 19-year-old soldiers were ready for drafting to France. In due course the War Office decided that Graduated battalions could be used for home defence while the men completed their training. The Graduated battalions then began to be transferred from the Reserve brigades to replace 2nd Line TF battalions in the Home Service divisions. They were renumbered from 201st upwards, but later were once again affiliated with a particular regiment and numbered as the 51st, 52nd or 53rd battalions of their regiment.
List of brigades
Reserve Brigades
Territorial Force Reserve Brigades
| Reserve brigade title | Battalions |
| Highland Reserve Brigade | 4th Battalion, Black Watch |
| Highland Reserve Brigade | 4th Battalion, Seaforth Highlanders |
| Highland Reserve Brigade | 4th Battalion, Gordon Highlanders |
| Highland Reserve Brigade | 5th Battalion, Argyll and Sutherland Highlanders |
| Lowland Reserve Brigade | 4th Battalion, Royal Scots |
| Lowland Reserve Brigade | 9th Battalion, Royal Scots |
| Lowland Reserve Brigade | 4th Battalion, Royal Scots Fusiliers |
| Lowland Reserve Brigade | 4th Battalion, King's Own Scottish Borderers |
| Lowland Reserve Brigade | 5th Battalion, Scottish Rifles |
| Lowland Reserve Brigade | 5th Battalion, Highland Light Infantry |
| Lowland Reserve Brigade | 6th Battalion, Highland Light Infantry |
| West Lancashire Reserve Brigade | 5th Battalion, King's |
| West Lancashire Reserve Brigade | 7th Battalion, King's |
| West Lancashire Reserve Brigade | 10th Battalion, King's |
| West Lancashire Reserve Brigade | 4th Battalion, South Lancashire Regiment |
| West Lancashire Reserve Brigade | 4th Battalion, South Lancashire Regiment |
| West Lancashire Reserve Brigade | 4th Battalion, Loyal North Lancashire Regiment |
| East Lancashire Reserve Brigade | 5th Battalion, Lancashire Fusiliers |
| East Lancashire Reserve Brigade | 4th Battalion, East Lancashire Regiment |
| East Lancashire Reserve Brigade | 4th Battalion, Border Regiment |
| East Lancashire Reserve Brigade | 5th Battalion, Manchester Regiment |
| Welsh Reserve Brigade | 4th Battalion, Cheshire Regiment |
| Welsh Reserve Brigade | 4th Battalion, Royal Welsh Fusiliers |
| Welsh Reserve Brigade | 4th Battalion, Welsh Regiment |
| Welsh Reserve Brigade | 4th Battalion, Shropshire Light Infantry |
| Welsh Reserve Brigade | 1st Battalion, Monmouthshire Regiment |
| Welsh Reserve Brigade | 1st Battalion, Brecknockshire Battalion |
| Welsh Reserve Brigade | 1st Battalion, Herefordshire Regiment |
| Northumbrian Reserve Brigade | 4th Battalion, Northumberland Fusiliers |
| Northumbrian Reserve Brigade | 4th Battalion, Green Howards |
| Northumbrian Reserve Brigade | 5th Battalion, Durham Light Infantry |
| West Riding Reserve Brigade | 5th Battalion, West Yorkshire Regiment |
| West Riding Reserve Brigade | 7th Battalion, West Yorkshire Regiment |
| West Riding Reserve Brigade | 4th Battalion, Duke of Wellington's Regiment |
| West Riding Reserve Brigade | 6th Battalion, Duke of Wellington's Regiment |
| West Riding Reserve Brigade | 4th Battalion, King's Own Yorkshire Light Infantry |
| West Riding Reserve Brigade | 4th Battalion, York and Lancaster Regiment |
| North Midland Reserve Brigade | 4th Battalion, Lincolnshire Regiment |
| North Midland Reserve Brigade | 4th Battalion, Leicestershire Regiment |
| North Midland Reserve Brigade | 5th Battalion, South Staffordshire Regiment |
| North Midland Reserve Brigade | 5th Battalion, Sherwood Foresters |
| North Midland Reserve Brigade | 5th Battalion, North Staffordshire Regiment |
| South Midland Reserve Brigade | 5th Battalion, Royal Warwickshire Regiment |
| South Midland Reserve Brigade | 7th Battalion, Royal Warwickshire Regiment |
| South Midland Reserve Brigade | 4th Battalion, Gloucestershire Regiment |
| South Midland Reserve Brigade | 7th Battalion, Worcestershire Regiment |
| South Midland Reserve Brigade | 4th Battalion, Oxfordshire and Buckinghamshire Light Infantry |
| South Midland Reserve Brigade | 4th Battalion, Royal Berkshire Regiment |
| East Anglian Reserve Brigade | 4th Battalion, Norfolk Regiment |
| East Anglian Reserve Brigade | 4th Battalion, Suffolk Regiment |
| East Anglian Reserve Brigade | 5th Battalion, Bedfordshire Regiment |
| East Anglian Reserve Brigade | 4th Battalion, Essex Regiment |
| East Anglian Reserve Brigade | 4th Battalion, Northamptonshire Regiment |
| East Anglian Reserve Brigade | 1st Battalion, Cambridgeshire Regiment |
| East Anglian Reserve Brigade | 1st Battalion, Hertfordshire Regiment |
| Home Counties Reserve Brigade | 4th Battalion, Queen's Regiment |
| Home Counties Reserve Brigade | 4th Battalion, Buffs |
| Home Counties Reserve Brigade | 5th Battalion, East Surrey Regiment |
| Home Counties Reserve Brigade | 4th Battalion, Royal Sussex Regiment |
| Home Counties Reserve Brigade | 4th Battalion, Royal West Kent Regiment |
| Home Counties Reserve Brigade | 7th Battalion, Middlesex Regiment |
| Wessex Reserve Brigade | 4th Battalion, Devonshire Regiment |
| Wessex Reserve Brigade | 4th Battalion, Somerset Light Infantry |
| Wessex Reserve Brigade | 4th Battalion, Duke of Cornwall's Light Infantry |
| Wessex Reserve Brigade | 4th Battalion, Hampshire Regiment |
| Wessex Reserve Brigade | 5th Battalion, Hampshire Regiment |
| Wessex Reserve Brigade | 4th Battalion, Dorset Regiment |
| Wessex Reserve Brigade | 4th Battalion, Wiltshire Regiment |
| 1st London Reserve Brigade | 1st Battalion, London Regiment |
| 1st London Reserve Brigade | 3rd Battalion, London Regiment |
| 1st London Reserve Brigade | 5th Battalion, London Regiment |
| 1st London Reserve Brigade | 6th Battalion, London Regiment |
| 1st London Reserve Brigade | 8th Battalion, London Regiment |
| 1st London Reserve Brigade | 9th Battalion, London Regiment |
| 1st London Reserve Brigade | 10th Battalion, London Regiment |
| 1st London Reserve Brigade | 1st Battalion, Honourable Artillery Company |
| 2nd London Reserve Brigade | 13th Battalion, London Regiment |
| 2nd London Reserve Brigade | 14th Battalion, London Regiment |
| 2nd London Reserve Brigade | 15th Battalion, London Regiment |
| 2nd London Reserve Brigade | 16th Battalion, London Regiment |
| 2nd London Reserve Brigade | 17th Battalion, London Regiment |
| 2nd London Reserve Brigade | 18th Battalion, London Regiment |
| 2nd London Reserve Brigade | 19th Battalion, London Regiment |
| 2nd London Reserve Brigade | 20th Battalion, London Regiment |
| 2nd London Reserve Brigade | 21st Battalion, London Regiment |
| 2nd London Reserve Brigade | 22nd Battalion, London Regiment |
| 3rd London Reserve Brigade | 13th Battalion, London Regiment |
| 3rd London Reserve Brigade | 15th Battalion, London Regiment |
| 3rd London Reserve Brigade | 16th Battalion, London Regiment |
| 3rd London Reserve Brigade | 17th Battalion, London Regiment |
| 3rd London Reserve Brigade | - |
| 3rd London Reserve Brigade | - |
| 3rd London Reserve Brigade | - |
| 3rd London Reserve Brigade | - |
| 3rd London Reserve Brigade | - |
| 3rd London Reserve Brigade | - |