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- Divisions and Brigades of The Allied Army in The Great War 1914 - 1918

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Prior to the First World War the largest unit in the British Army was a Division and the Army was much smaller than the French or German Armies prior to commencement of hostilities in August 1914. Never before had so vast a conflict been fought and its immediate effect was to increase manpower and merge units in large configurations to match its opponent’s dispositions.

An Order of Battle (often shortened to ORBAT) is the identification, strength, command structure and disposition of the personnel, units and equipment of any military force. It is an organisational view of the army.

Battalion (Infantry)

The structure of the Army basically starts with the soldier who is a member of a Battalion, consisting of about 1000 men, which is normally organised into a number of companies (usually 4 and a Headquarters company), which are further subdivided into platoons and sections. This basically enables supervision to be taken down through the various grouping to the smallest section and individual.


The next grouping is by Regiment which is the historical backbone of the Army carrying the Monarch’s Colours which display Battle Honours from the past. Most Regiments have a traditional link with towns or regions where they were originally raised or created. During peacetime most Regiments have one or two Battalions, however during wartime extra battalions including reserve battalions are called up or mobilized and recruits sought usually encouraging men to join their local regiment.


The next upward chain of command is the Brigade which then consisted of 4 infantry battalions (from different regiments) and other special groups which will be explained later along with the Division.


Then we come to the traditional Division which had a structure laid down as the largest unit for war in the past. The Division is so important to the overall conduct of the war that it will also be explained at the end of this guide.


The huge numbers raised to fight in this largest and costliest of wars resulted in the need for further coordination of Divisions resulting in the creation of Corps and resulted in many early appointments of General Officers at this new grouping level.


Finally and again to coordinate very large operation groups, Armies were formed which had a minimum of two Corps attached. The British Command eventually had 5 Armies in France and Flanders.


Overall command of all the above units rested with General Headquarters which was itself commanded by the War Office in London.

Changing Tactics as the war progresses.

Now there is a need to explain the higher echelons of command and this requires some understanding of the effects of this large scale warfare and the developing roles of infantry support.

Prior to this war fighting was on land or at sea (Naval Battles) with some Naval support in smaller wars further afield. Now it was to be Land, Sea and - a new concept – Air.

Other units were already in existence to support the Infantry mainly Cavalry (mounted infantry) and Artillery.


Soldiers were organised on the same lines as Infantry Regiments but with sword, lance and Horse. Most were eventually dismounted and trained as infantry as the cavalry role became outdated in this more mechanised war.


Soldiers in the Artillery would serve in a Battery or Ammunition Column. A Battery consisted of two and later four guns and a Brigade consisted of usually four Batteries. Artillery was further divided into Field Guns (Royal Field Artillery and Royal Horse Artillery) and Heavy Guns/Howitzers (Royal Garrison Artillery). As the war progressed ever increasing concentration of firepower led to increased use of Divisional Artillery Grouping of Brigades and Ammunition Columns. Artillery played a huge part in trench warfare and it took the allies a long time to gain superiority in this field.

Other Corps.

Now we introduce a different use and meaning of the word Corps. So far we have used it as an overall command level created in this war to command groups of Divisions. Corps was previously in use as a regiment (Kings Royal Rifle Corps) and for special support units such as Royal Engineers, Royal Army Medical, Army Service, Tank and Royal Flying all of which had Corps in their titles. (Some had the Royal added to their titles after the war).

Machine Gun Corps.

Initially each Battalion had two Machine Gun crews and started the war with the Maxim Machine Gun. This was later changed to the Vickers machine gun – similar design but lighter and better firing mechanism. As the war bogged down into trench warfare the need for greater concentration of firepower became obvious so machine gun were removed in stages from the infantry battalions and two schools were set up to train machine gunners in new tactics forming specialist machine gun companies. Each Brigade was given a machine gun company and each Division got a Divisional machine gun company. All these company personnel became part of the Machine Gun Corps. However the Corps did not survive for long after the war as lighter and faster semi-automatic weapons became available at all levels for troops. In order to maintain and improve the firepower of infantry battalions after removal of their machine guns, the even lighter Lewis Gun was issued as they became available, initially 4 then subsequently 8 Lewis guns per battalion – increasing mobility and firepower considerably.

Two New Corps

Totally new to warfare were the concept of Tanks and Planes which led to the formation of the Royal Tank Corps (Royal was added later) which was originally formed as the Heavy Division of the Machine Gun Corps. The introduction of aeroplanes led to the setting up of the Royal Flying Corps, forerunner to a separate arm of the Armed Forces - the Royal Air Force.

The British Armies of 1914-1918

In France and Flanders, the size of the British army was eventually such that it was subdivided into five Armies, each commanded by a Lieutenant-General. Armies were also formed at home and the force in Salonika also went by the title, although those in Gallipoli, Italy and Palestine did not.

Now for that explanation of Brigade and Division Structure.

At the outbreak of was the standard British Army Division consisted of:

3 Brigades, each consisting: 4 Infantry Battalions, 1 Machine Gun Company** and 1 Trench Mortar Battery

Divisional Troops consisting: 1 Infantry Battalion, 1 Pioneer Battalion and 1 Machine Gun Company** (formed into Machine Gun Battalion 1918)

Divisional Mounted Troops: 1 Cavalry Battalion and 1 Cyclist Battalion

Divisional Artillery: 3 Brigades Royal Field Artillery, 1 Howitzer Battery RFA, 1 Heavy Battery Royal Garrison Artillery, 1 Divisional Ammunition Column, 1 Heavy Trench Battety RFA and 1 Medium Trench Battery RFA

Royal Engineers: 3 Field Companies and 1 Signal Company

Royal Army Medical Corps: 3 Field Ambulance Companies

Divisional Train Army Service Corps: Mobile Veterinary Section

From this list one can observe that a Division was a reasonably self-sufficient military unit but it still needed a massive amount of logistic support. Bearing in mind that there were more than 50 Divisions in the Western Front at various stages in the war gives us some idea of the amount of labour needed to keep this vast army supplied with men, equipment, ammunition, animals, food and fodder.

There were many other special units but it is hoped that this guide give a reasonably broad approach to understanding the basics of the British Army’s organisation – and reorganisation - for the pursuit of its objectives in the Great War.

Allied Divisions

Allied Brigades

This section is still under construction

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