The Manufacturing Departments of the Ordnance Office were the predecessors of the modern Royal Ordnance Factories.
The oldest was Woolwich Arsenal, renamed the Royal Arsenal in 1805. The Warren at Woolwich was first used for the proof of ordnance in 1651 and Tower Place was acquired for storage in 1670. Manufacture commenced when the Laboratory (later the Royal Laboratory) was established in 1696. Subsequently the Royal Brass Foundry for the manufacture of brass ordnance was founded in 1716 and the Royal Carriage Department was added in 1803.
The manufacture of gunpowder commenced with the purchase of a privately-owned mill at Faversham in 1759 and the establishment there of the Royal Powder Mill. This was closed in 1825. Meanwhile another powdermill was purchased at Waltham Abbey in 1787 and named the Royal Gunpowder Factory. Powder was stored at Greenwich from an early date until 1763, when the magazine there was moved to Purfleet. It was also stored from at least as early as 1695 at Upnor Castle (later the Upnor Armaments Supply Depot).
The manufacture of small arms commenced in 1804 at the Tower of London and moved in 1807 to the Royal Manufactory of Small Arms at Lewisham. The Royal Small Arms Factory site at Enfield was purchased in 1811 and operations commenced in 1816; the work of the Lewisham establishment was transferred there in 1818.
When the Ordnance Office was dissolved in 1855, the manufacturing departments, namely the Royal Arsenal at Woolwich, the Royal Gunpowder Factory at Waltham Abbey and the Royal Small Arms Factory at Enfield, were transferred to the War Office. There they were the concern successively of the Artillery, Ordnance and Artillery and Stores Departments or Divisions. In 1887, when they were renamed the Royal Ordnance Factories, control passed to the financial secretary's Civil Department, from which in 1899 they returned to the Ordnance Department.
Between 1915 and 1920 they were the concern of the Ministry of Munitions, but after the war they returned to the Department of the Master General of the Ordnance. In 1936 they were transferred to the Director General of Munitions Production.
In August 1939 responsibility for the Ordnance Factories was transferred to the Ministry of Supply. There, at first, it was a directorate under the director-general of munitions production. Later it became itself a directorate general under the controller general of munitions production. In 1959 the Ordnance Factories returned to the control of the War Office.