The Dorchester Depot Barracks were built between 1877 and 1881 on the site of a Militia barracks, which had been established there little over a decade earlier. Their creation took place as part of the Cardwell Reforms which encouraged the localisation of British military forces. The site included a large parade ground, which was laid out between the Keep (or armoury) and the building now known as the 'little keep' and flanked by brick-built barrack blocks (including separate accommodation for officers and other ranks), the officers' mess, a gymnasium, stores, offices and other ancillary buildings.