British Army operations in the First World War

1. Why use this guide?

This guide will help you find records at The National Archives relating to military operations and actions in the First World War, planned and carried out by the:

• British Army at home and overseas
• Indian Army
• Canadian, New Zealand, South African or Indian forces (also known as dominion forces) under British command
• Colonial forces under British command
• Royal Flying Corps

The records include details of:

• invasions
• battles
• daily activities of army units (as recorded in unit war diaries)

The guide does not cover records of:

• personnel (for records of soldiers who served in the First World War see our guide to British Army soldiers after 1913)
• supply
• technological research

2. Essential information

This guide focuses on War Office records (department code WO), covering the British Army only.

You can find many other First World War military operational records in other departments. For example, Royal Navy records are in ADM, and Royal Naval Air Service and Royal Air Force records are in AIR.

2.2 British Army structure

During the First World War, the British Army was divided into a complicated hierarchical structure of numerous units and sub-units. The structure, down to battalion level, was as follows:

1. General Headquarters/British Expeditionary Force (BEF)

2. Army (Western Front only; by Oct 1916 the BEF consisted of the 1st, 2nd, 3rd, 4th and 5th Armies)

3. Corps (consisted of two or more divisions)

4. Division (consisted of three or four regiments/brigades)

5. Regiment/Brigade (regiments consisted of two or more battalions; brigades consisted of four or more battalions from different regiments)

6. Battalion (usually 300-1300 soldiers)

3. How to conduct a general search

You can search Discovery, our catalogue, using keywords.

Not all of the records have been catalogued in detail, and many have not been digitised. To view non-digitised records you will need to visit The National Archives at Kew or pay for research.

Many army units have been catalogued using abbreviations (for example, 'Fd. Regt.' instead of 'Field Regiment'), so you may have to experiment with different search terms and formats.

However, keyword searching can be a good way to begin. Try searching by:

• name of battle (for example, 'Somme')
• name of operation or campaign (for example, 'Gallipoli Campaign')
• name of a theatre of war (for example, 'Western Front' or 'Dardanelles')
• name of army unit - try different formats (for example, 'Royal Field Artillery' or 'RFA')

Restrict your search to the appropriate date range and search within reference WO.

Consult the Dictionary of military and technological abbreviations and acronyms (Routledge and Kegan Paul, 1983) by Bernhard Pretz for help with deciphering the text in some operations records, particularly unit war diaries.

For further general guidance, consult The First World War: the Essential Guide to Sources in the UK National Archives by IFW Beckett (Public Record Office, 2002).

4. Unit war diaries 1914-1922

First World War unit war diaries cover the hostilities as well as some post-war operations, including the Army of Occupation.

They were kept by:

• British, Dominion, Indian and Colonial units in the United Kingdom, France, Flanders, Italy, Gallipoli, Mesopotamia, Palestine, Salonika and Russia
• the Royal Flying Corps
• specialist units, such as military hospitals

4.1 All units except Royal Flying Corps

Many of the unit war diaries in series WO 95 have been digitised. For more information and instructions on how to search, see our guide to British Army war diaries 1914-1922.

Alternatively, use our catalogue to search the entire collection, including those diaries that have not been digitised. Use all or part of the regiment or unit name and battalion number (15, not 15th) as keywords, restricting your search to reference WO 95.

If you can't find the diary you're looking for in WO 95, try a search in WO 154, a series containing information on courts martial extracted from WO 95.

In most cases, there are copies of diaries with the regiments themselves or in regimental museums. Use the ARCHON Directory to find a regimental museum.

4.2 Royal Flying Corps

Search our catalogue, searching within AIR 20 or AIR 1, for Royal Flying Corps unit war diaries. Your search terms should take one of the following formats:

• a squadron or wing number AND "R.F.C."
• a squadron number AND "Royal Flying Corps"

5. Records of Cabinet

For records of military operations within Cabinet records, begin by searching our Cabinet papers website (£there will be a charge). You can also browse selected records on the theme of war.

To find further records of the Cabinet Office, search our catalogue restricted to the department CAB and the relevant year range.

The records include:

• drafts of official war histories and narratives in CAB 44
• correspondence, maps, papers, personal accounts, photographs and private war diaries used to prepare official war histories in CAB 45
• information on the East Africa campaign and other documents used to prepare official histories in CAB 103

6. Other operational records

There are numerous other records series that contain details of First World War operations and campaigns. Some of the most significant are:

• correspondence and papers of military headquarters in WO 158
• miscellaneous papers including short histories of the campaigns in Russia and the Dardenelles in WO 161
• intelligence summaries in WO 157
• photographs of Gallipoli, Palestine, and Italian Campaigns in WO 317, WO 319 and WO 323

There are other records series which cover a broader range of years and subjects and contain details of First World War operations. Use the advanced search option in our catalogue to search within one or all of the following references:

• WO 32
• WO 33
• WO 106

You can also browse these series in our catalogue. Please be aware that this may prove time consuming as they are very large.

For advice on map collections, see our Military maps of the First World War research guide. 

7. Orders of Battle and deployment of units

Published in several volumes, the Order of Battle of Divisions list month by month the location of each unit, and the division or army to which they were attached. They are arranged by division (not by regiment).

Similarly, within WO 95 are several sets of files covering orders of battle, British military missions and deployment of units.

The paper version of the catalogue for WO 95, in the reading rooms at The National Archives at Kew, is accompanied by separate indexes which provide details of the allocation of battalions to fields of battle as well as their reallocation from one brigade or division to another.

8. Further reading

The following recommended publications are available in The National Archives' Library. Where indicated a publication is also available to buy at The National Archives' Bookshop.

M Brown, The Imperial War Museum book of the First World War; a great conflict recalled in previously unpublished letters, diaries, documents and memoirs (Sidgwick & Jackson, 1991)

Peter Chasseaud, Topography of Armageddon: a British trench map atlas of the Western Front, 1914-1918 (Mapbooks, 1991)

Douglas Haig, Douglas Haig: War diaries and letters, ed. Gary Sheffield and John Bourne (Weidenfeld & Nicolson, 2005) 

Alfred Chevallier Parker, The diaries of Parker Pasha, ed. HVF Winstone (Quartet Books, 1983) 

William Spencer, First World War Army Service Records (The National Archives, 2008) - Available to buy

Robert Alan Watson, War Diaries of John Alan Watson RGA: 13th Siege Battery April 1915 - October 1915, 76th Siege Battery April 1916 - December 1916 (1994)