[1] As part of the reorganisation of home defence forces by Field Marshal Sir John French, Commander-in-Chief, Home Forces, the Royal Defence Corps was created to “...carry out duties connected with the local defence of the United Kingdom, including those hitherto performed by the Supernumerary Territorial Force Companies....."[2] The role of the corps was thus to provide troops for security and guard duties inside the United Kingdom, guarding important locations such as ports, bridges and railways, as well as prisoner-of-war camps.
In addition to the Supernumerary Companies, 18 (Home Service) Garrison battalions of line infantry regiments became part of the RDC.
Garrison battalions were composed of soldiers either too old or medically unfit for active front-line service; the Home Service status indicated they were unable to be transferred overseas.
[6] Uniform distinctions included a cap badge of the royal cipher and crown within a circlet formed by the words 'ROYAL DEFENCE CORPS'[7] and a brass 'RDC' shoulder title.
It was finally disbanded in 1936, when its functions were taken over by the National Defence Companies of the Territorial Army.