Records created or inherited by the War Office, Armed Forces, Judge Advocate General, and related bodies relating to the administration of the armed forces.
Comprises records of:
- General War Office records
- Chief of the (Imperial) General Staff and its directorates
- Commander-in-Chief, Military Secretary and Army Council
- Army Medical services
- Other administrative departments of the War Office
- Finance departments
- Central Department of the Permanent Secretary of State
- Land Branch
- Board of General Officers
- Royal Chelsea and Kilmainham Hospitals
- Constable of the Tower of London
- Research establishments
- Armed forces records from commands, headquarters, regiments and corps
- Auxiliary forces
- Army in Ireland
- Armed forces service records
- Private office papers and private collections
- Commissions, committees and councils, etc
- Ordnance Office and its War Office successors
- Judge Advocate General
WO 56, WO 125, WO 200, WO 249 and WO 289 are numbers not used.
WO 20 and WO 21 were transferred to other series before 1905.