Barrack accommodation on Western Heights was further increased by the building of another barracks to the south-west, South Front Barracks, in the 1860s. In contrast to the Grand Shaft Barracks, which had come to be seen as vulnerable due to technological advances in artillery, the accommodation at South Front Barracks was mainly built within bomb-proof casemates within the ditch of the southern defensive line (which was constructed at the same time above Archcliffe Fort). Between these casemated barracks and the Citadel Road, married quarters and ancillary buildings were provided, on a series of three stepped terraces built into the hillside. The casemated barracks had accommodation for 400 soldiers and the married quarters accommodated a further 120 married soldiers with their families. While the married quarters continued to be occupied in the 20th century, by 1912 the casemates were no longer in use as barracks, serving instead as offices for the Royal Garrison Artillery.