In August 1914, the officer class in the British army was a small and privileged élite numbering only 15,000 men. During the course of the war, a further 235,000 individuals were given either permanent or, more frequently, temporary commissions. The pressing need for an expanded officer corps enabled men from a wider variety of social and educational backgrounds to become 'temporary gentlemen'.

The National Archives holds records for the majority of British army officers who served in the First World War. However, the files of officers who were still serving after 31 March 1922, as well as those of officers who rejoined the army after this date, are still held by the Ministry of Defence.

Moreover, the surviving officers' records themselves are incomplete. Of the three original parts to an officer's file - the record of service form (AF B 199), the confidential reports (AF B 196) and the correspondence file - only the latter generally still exists. The AF B 199s and 196s for officers commissioned after 1901, which were stored separately from the correspondence files at the War Office repository in Arnside Street, were destroyed in the German bombing raid of September 1940.

The National Archives' largest collection relating to officers who served in the First World War is the WO 339 series, which contains files on nearly 140,000 individuals. Most of them pertain to the 'temporary gentlemen' who were commissioned as officers for the duration of the war only, among them J R R Tolkien.

WO 339 also contains files on many of the individuals who already possessed commissions in the regular army before war broke out, as well as the records of British army 'other ranks' (i.e. non-officers) who received commissions in the Indian army between 1914 and 1918. Material on officers (both European and Indian) in the Indian army can also be found at the British Library. Most of the material in WO 339, it should be noted, consists ofcorrespondence about an officer and his service rather than a service record per se (see our guide to British Army officers after 1913).

Territorial Force

Royal Engineers

Militia

WO 138 contains files on famous British army officers (such as Field Marshal Douglas Haig and the poet Wilfred Owen ) and files relating to officers who were either dismissed during the war or whose service led to official War Office enquiries after the war.

The National Archives also holds the Army List, a basic record of all officers holding commissions in the British army. It was published in various formats during the First World War (monthly, quarterly and bi-annually) and can be used to trace a particular officer in the regulars, the Territorials and the reserves.

The Army List also contain information about British army officers who saw service in Africa (in either the King's African Rifles or the West African Frontier Force) and the officers of the Dominion forces that formed part of the British army. Further lists of officers can be found in the individual regimental histories that are available in The National Archives library.

For further information, see The National Archives' research guides.