During 1855 the Board of Ordnance was abolished as a result of its perceived poor performance during the Crimean War.
This powerful independent body, dating from the 15th century, had been directed by the Master-General of the Ordnance, usually a very senior military officer who (unlike the Secretary at War) was often a member of the Cabinet.
The records of the War Office are kept by The National Archives with the code WO.
Between 1906 and its abolition during 1964, the War Office was based in a large neo-Baroque building, completed during 1906, located on Horse Guards Avenue at its junction with Whitehall in central London.
The four most important were the Commander-in-Chief of the Forces, the Secretary at War and the Secretary of State for War.
Others who performed specialist functions were the controller of army accounts, the Army Medical Board, the Commissariat Department, the Board of General Officers, the Judge Advocate General of the Armed Forces, the Commissary General of Muster, the Paymaster General and the Home Office (before 1782 the twin secretaries of state).
The disastrous campaigns of the Crimean War resulted in the consolidation of all administrative duties during 1855 as subordinate to the Secretary of State for War, a Cabinet job.
During August 2013 it was announced that the former War Office building would be sold on the open market.
On 1 April 1920, it employed 7,434 civilian staff; this had decreased to 3,872 by 1 April 1930.
Its responsibilities and funding were also reduced.
Clement Attlee continued this arrangement when he came to power during 1945 but appointed a separate Minister of Defence for the first time during 1947.
During 1964, the present form of the Ministry of Defence was established, unifying the War Office, Admiralty, and Air Ministry.
Issues of strategic policy during wartime were managed by the Northern and Southern Departments (the predecessors of today's Foreign Office and Home Office).