It was established with headquarters in Königsberg (now Kaliningrad, Russia). Initially, the Corps catchment area comprised the entire Province of East Prussia, but from 1 October 1912 the southern part of the Province was transferred to the newly formed XX Corps District.[1]
In peacetime, the Corps was assigned to the I Army Inspectorate, which became the 8th Army at the start of the First World War.[2] The corps was still in existence at the end of the war,[3] and was disbanded with the demobilisation of the German Army after World War I.
From formation in 1820, the Corps commanded two divisions: 1st Division and 2nd Division.[6] These were joined by 37th Division when it was formed on 1 April 1899. 37th Division was transferred to XX Corps when it was formed on 1 October 1912.[7]
The 25 peacetime Corps of the German Army (Guards, I - XXI, I - III Bavarian) had a reasonably standardised organisation. Each consisted of two divisions with usually two infantry brigades, one field artillery brigade and a cavalry brigade each.[8] Each brigade normally consisted of two regiments of the appropriate type, so each Corps normally commanded 8 infantry, 4 field artillery and 4 cavalry regiments. There were exceptions to this rule:
V, VI, VII, IX and XIV Corps each had a 5th infantry brigade (so 10 infantry regiments)
On mobilization on 2 August 1914, the Corps was restructured. The 1st and 2nd Cavalry Brigades were withdrawn to form part of the 1st Cavalry Division[12] and the 43rd Cavalry Brigade was broken up and its regiments assigned to the divisions as reconnaissance units. The Divisions received engineer companies and other support units from the Corps headquarters. In summary, I Corps mobilised with 24 infantry battalions, 8 machine gun companies (48 machine guns), 8 cavalry squadrons, 24 field artillery batteries (144 guns), 4 heavy artillery batteries (16 guns), 3 pioneer companies and an aviation detachment.
Cron, Hermann (2002). Imperial German Army 1914-18: Organisation, Structure, Orders-of-Battle [first published: 1937]. Helion & Co. ISBN1-874622-70-1.
Ellis, John; Cox, Michael (1993). The World War I Databook. Aurum Press Ltd. ISBN1-85410-766-6.
Haythornthwaite, Philip J. (1996). The World War One Source Book. Arms and Armour. ISBN1-85409-351-7.
Wegner, Günter (1993). Stellenbesetzung der deutschen Heere 1815-1939, Bd. 1. Biblio Verlag, Osnabrück.
Histories of Two Hundred and Fifty-One Divisions of the German Army which Participated in the War (1914–1918), compiled from records of Intelligence section of the General Staff, American Expeditionary Forces, at General Headquarters, Chaumont, France 1919. The London Stamp Exchange Ltd (1989). 1920. ISBN0-948130-87-3.
The German Forces in the Field; 7th Revision, 11th November 1918; Compiled by the General Staff, War Office. Imperial War Museum, London and The Battery Press, Inc (1995). 1918. ISBN1-870423-95-X.
Prussia / 
German Empire
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