British Army First World War reserve brigades

At the start of the war volunteers in the vast majority of cases joined their local infantry regiment's reserve battalion.

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.

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.

[1] In addition, recruits flooded into the drill halls of the part-time Territorial Force (TF), which had largely volunteered for overseas service.

This legislation did not apply to Ireland, despite its then status as part of the United Kingdom (but see Conscription Crisis of 1918).

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.

The reserve brigades had now been concentrated at large training camps, and the TR had a total establishment of 209,537 men.

In due course the War Office decided that Graduated battalions could be used for home defence while the men completed their training (as was the case with the SR).