I Corps (United Kingdom)


I Corps was an army corps in existence as an active formation in the British Army for most of the 80 years from its creation in the First World War until the end of the Cold War, longer than any other corps. It had a short-lived precursor during the Waterloo Campaign. It served as the operational component of the British Army of the Rhine during the Cold War, and was tasked with defending West Germany.

Napoleonic precursor

Assembling an army in Belgium to fight Napoleon's resurgent forces in the spring of 1815, the Duke of Wellington formed it into army corps, deliberately mixing units from the Anglo-Hanoverian, Dutch-Belgian and German contingents so that the weaker elements would be stiffened by more experienced or reliable troops. As he put it: 'It was necessary to organize these troops in brigades, divisions, and corps d’armee with those better disciplined and more accustomed to war'. He placed I Corps under the command of the Prince of Orange and it was this corps that was first contacted by the advancing French at Quatre Bras on 16 June 1815. However, Wellington did not employ the corps as tactical entities, and continued his accustomed practice of issuing orders directly to divisional and lower commanders. When he drew up his army on the ridge at Waterloo, elements of the various corps were mixed up, and although he gave the Prince of Orange nominal command of the centre, that officer had different forces under him. Subsequent to the battle, the corps structure was re-established for the advance into France, I Corps being commanded by Maj-Gen Sir John Byng, the Prince of Orange having been wounded at Waterloo.

Composition of I Corps in the Waterloo Campaign

: General The Prince of Orange
After Waterloo the army corps structure largely disappeared from the British Army, except for ad hoc formations assembled during annual manoeuvres. In 1876 a Mobilisation Scheme for eight army corps was published, with 'First Corps' based on Colchester. In 1880 First Corps' organization was:
This scheme had been dropped by 1881. The Stanhope Memorandum of 1891 laid down the policy that after providing for garrisons and India, the army should be able to mobilise three army corps for home defence, two of regular troops and one partly of militia, each of three divisions. Only after those commitments, it was hoped, might two army corps be organised for the unlikely eventuality of deployment abroad.
When the Second Anglo-Boer War was imminent in September 1899, a field army, referred to as the Army Corps was mobilised and sent to Cape Town. It was, in fact, 'about the equivalent of the First Army Corps of the existing mobilization scheme', and was placed under the command of Gen Sir Redvers Buller, General Officer Commanding-in-Chief of Aldershot Command. However, once in South Africa the corps never operated as such, and the three divisions were widely dispersed.
The 1901 Army Estimates introduced by St John Brodrick allowed for six army corps based on the six regional commands of which only I Corps and II Corps would be entirely formed of regular troops. However, these arrangements remained theoretical, the title 'I Corps' being added to Aldershot Command. In early October 1902 a memorandum was issued showing the organization and allocation of the 1st Army Corps, to which Sir John French had recently been appointed in command:
In 1907 the title changed to 'Aldershot Corps' but reverted to simply 'Aldershot Command' the following year. Finally, the Haldane Reforms of 1907 established a six-division British Expeditionary Force for deployment overseas, but only Aldershot Command possessed two infantry divisions and a full complement of 'army troops' to form an army corps in the field.

First World War

Pre-war planning for the British Expeditionary Force did not envisage any intermediate headquarters between GHQ and the six infantry divisions, but it was assumed that if corps HQs became necessary, then the GOC Aldershot Command would automatically become GOC I Corps in the field. On mobilisation in August 1914 the decision was made to conform to the two-division army corps organisation employed by the French armies alongside which the BEF was to operate. Sir Douglas Haig, then commanding at Aldershot, therefore took I Corps HQ to France with 1st Division and 2nd Division under command, and it remained on the Western Front throughout the war. It had a peripheral part at the Battle of Mons, then saw hard fighting at the Battle of the Aisne and First Battle of Ypres in 1914, at the Battle of Aubers Ridge in the Spring of 1915 and alongside the Canadian Corps at the Battle of Hill 70, as well in many other large battles of the First World War.

Composition of I Corps in First World War

The composition of army corps changed frequently. Some representative orders of battle for I Corps are given here.
Order of Battle at Mons 23 August 1914
General Officer Commanding: Lieut-Gen Sir Douglas Haig
  • Brigadier-General, General Staff : J.E. Gough VC
  • Brigadier-General, Royal Artillery: H.S. Horne
  • Colonel, Royal Engineers: Brig-Gen Spring R. Rice
  • 1st Division
  • 2nd Division
  • Army Troops attached
  • * 1st Army HQ Signal Company, Royal Engineers
  • ** D Section
  • ** G, K & L Sections
  • * No 2 Section, 1st Printing Company, Royal Engineers
  • * No 1 Bridging Train, Royal Engineers
  • * B Squadron, North Irish Horse
  • * Company, 1st Bn Cameron Highlanders
  • * B & C Sections, No 19 Field Ambulance, RAMC
By the time of the battles of Aubers Ridge and Festubert, I Corps still had 1st and 2nd Divisions under command, but had been reinforced by 47th Division of the Territorial Force, and 1st Canadian Division. Once the era of trench warfare had set in on the Western Front, the BEF left its army corps in position for long periods, so that they became familiar with their sector, while rotating divisions as they required rest, training, or transfer to other sectors.
From May 1916 to August 1917, I Corps Cavalry Regiment was provided by the 1st South Irish Horse.
On 25 September 1918, for the final battles, I Corps was transferred from First Army to Sir William Birdwood's Fifth Army.
Order of Battle during the final advance in Artois 2 October-11 November 1918
General Officer Commanding: Lieut-Gen Sir Arthur Holland

BGGS: Brig-Gen G.V. Hordern

Deputy Adjutant & Quartermaster-General: Brig-Gen N.G. Anderson

Commander, Royal Artillery: Brig-Gen H.C. Sheppard

Commander, Heavy Artillery: Brig-Gen F.G. Maunsell

Commander, Engineers: Brig-Gen H.W. Gordon

Battle of France

During the Second World War, I Corps' first assignment was again to the British Expeditionary Force where it was commanded by General Sir John Dill, and then Lieutenant General Michael Barker from April 1940. After the Germans broke through Allied lines in the Battle of France in May 1940, the BEF was forced to retreat to Dunkirk for evacuation to England. The Commander-in-Chief of the BEF, General Lord Gort, ordered Barker to form the rearguard with I Corps to cover the evacuation, and surrender to the Germans as a last resort. However, the acting commander of II Corps, Major General Bernard Montgomery, advised Gort that Barker was in an unfit state to be left in final command, and recommended that Major General Harold Alexander of the 1st Division should be put in charge. Gort did as Montgomery advised, and in the event the bulk of I Corps was successfully evacuated. As Montgomery recalled: '"Alex" got everyone away in his own calm and confident manner'.