Cambridge Battery was built between 1862 and 1868 on what had been the old Laboratory for Fort Ogilvie and Prince of Wales Tower. It therefore comes after the 1860 Royal Commission on the the Defence of British Ports and was an RML battery. The battery mounted five 10-inch 18 ton RML guns and three 7-inch 7 ton RML guns. The battery is at 65 feet and set back a little from the shore line and was originally called the UPPER BATTERY. The gun line was lade out in a semi-circle.
Cambridge Battery was upgraded in the run up to World War 1 with two 6-inch BL Mark VII guns which were later moved to Sydney Harbour in Nova Scotia. Plans dated from 1902 show the two 6-inch BL positions with an underground magazine between the two gun pits. There was also an underground shelter for twenty three men on the East side of the magazine. (TNA WO 78/3960)