The Territorial and Reserve Forces Act 1907 (7 Edw. 7. c. 9) was an act of the Parliament of the United Kingdom that reformed the auxiliary forces of the British Army by transferring existing Volunteer and Yeomanry units into a new Territorial Force (TF); and disbanding the Militia to form a new Special Reserve of the Regular Army. This reorganisation formed a major part of the Haldane Reforms, named after the creator of the act, Richard Haldane.
The lessons learned during the South African War of 1899-1902 had reinforced the idea that the Regular Army was not capable of fighting a prolonged full-scale war without significant assistance; almost all regular units in the United Kingdom had been deployed overseas within four months of the outbreak of hostilities. Furthermore, by the end of the first year of fighting, the Regular Reserve and the Militia Reserve had been entirely exhausted. (Regular reservists were members of the Regular Army who had retired from the active-duty portion of their service but remained available for the callout. The Militia Reserve was a pool of individuals within the Militia, who accepted an overseas service liability). There had been no thought before the war about the wider use of auxiliary forces overseas; in the event, volunteers had been used on an ad-hoc basis, and a new auxiliary arm (the Imperial Yeomanry) was formed to provide specialist troops, but it was clear that a more effective system was required in future. A number of attempts at reform under the Conservative government of 1901-1905 had failed to make any lasting changes to the system and left the auxiliary forces disorganised and demoralised.