Before 1855 the supply of guns and ammunition to the Royal Navy was the responsibility of the Ordnance Board, which was also concerned with supplying ordnance to the Army and which tended to concentrate on the latter function, although naval officers served on the board and on the Ordnance Select Committee which succeeded it. The Ordnance Board was abolished in May 1855, its responsibilities for naval ordnance passed to the War Office, where a naval officer was appointed Naval Director-General of Artillery within the Artillery Branch. He retained that title from 1858 to 1868, when he was also Director of Stores, War Office ; he was also the Vice-President of the Ordnance Select Committee.
A Director-General, subsequently Director of Naval Ordnance, in the Controller's Department of the Admiralty was first appointed in 1866, but he did not take over procurement of naval ordnance from the War Office until 1888 or custody and supply until 1891, when a Naval Ordnance Department was finally established at the Admiralty from inception until 1917
By stages from 1908 the Admiralty also took over responsibility from the War Office for inspecting naval ordnance when a Chief Inspector of Naval Ordnance was appointed. The Royal Ordnance Factories, under the control of the War Office, continued, however, to manufacture naval ordnance though a large proportion, including most of the heaviest guns, was let to private contract.
From 1917 until the department was responsible for mines and torpedoes. Between 1918 and 1923 and again from 1939 there was a separate Armament Supply Department.The Naval Ordnance Inspection Department was set up in 1922 to control quality in the manufacture and testing of weapons and ammunition for the fleet. Chemical and metallurgical analysis was carried out at its laboratories at Sheffield (the Bragg laboratory) and Caerwent.
During the First World War the directorate was divided, and a separate Department of the Director of Torpedoes and Mining was created. After the Second World War in 1946 this became the Underwater Weapons Department. The Bragg laboratory, so-called from 1938, continued unchanged until 1968, when its chemical analysis work became part of the Army Department's Directorate of Chemical Inspection at Woolwich. From 1940 to 1945 there was a Miscellaneous Weapons Development Department.
In 1958 the two were re-united as divisions of the Weapons Department, under the Director General of Weapons (Director General, Weapons from 1960 to 1964). Bragg continued as the Naval Ordnance Inspection (later Service) and Metallurgical Unit (NOIMU, later NOSMU) until 1984 when it was closed and its work transferred to Woolwich. Caerwent laboratory continued investigating propellants until 1971.