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XXI Army Corps
XXI. Armee-Korps
Stab eines Generalkommandos.svg
Flag of the Staff of a Generalkommando (1871–1918)
Active 1 October 1912 (1912-10-01)–1919 (1919)
Country  German Empire
Type Corps
Size Approximately 44,000 (on mobilisation in 1914)
Garrison/HQ Saarbrücken

World War I

Battle of the Frontiers

The XXI Army Corps / XXI AK (German language: XXI. Armee-Korps) was a corps level command of the German Army, before and during World War I.

As the German Army expanded in the latter part of the 19th Century and early part of the 20th Century, the XXI Army Corps was set up on 1 October 1912 in Saarbrücken as the Generalkommando (headquarters) for the districts of Koblenz, Trier and part of Alsace-Lorraine.[1] It took over command of 31st Division from XV Corps and the newly formed 42nd Division (the last division to be formed by the peacetime army). General der Infanterie Fritz von Below, former commander of 1st Guards Division, took command.[2]

It was assigned to the VII Army Inspectorate.[3] but joined the predominantly Bavarian 6th Army at the start of the First World War. It was still in existence at the end of the war[4] in the 5th Army, Heeresgruppe Gallwitz on the Western Front.[5]

Peacetime organisation

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.[6] 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)
II, XIII, XVIII and XXI had a 9th infantry regiment
I, VI and XVI Corps had a 3rd cavalry brigade (so 6 cavalry regiments)
the Guards Corps had 11 infantry regiments (in 5 brigades) and 8 cavalry regiments (in 4 brigades).[7]

Each Corps also directly controlled a number of other units. This could include one or more

Foot Artillery Regiment
Jäger Battalion
Pioneer Battalion
Train Battalion

World War I

Organisation on mobilisation

On mobilization on 2 August 1914 the Corps was restructured. 42nd Cavalry Brigade was withdrawn to form part of the 7th Cavalry Division[11] and the 31st Cavalry Brigade was broken up and its regiments assigned to the divisions as reconnaissance units. Divisions received engineer companies and other support units from the Corps headquarters. Unusually, the Corps retained its 9th infantry regiment on mobilisation. In summary, XXI Corps mobilised with 27 infantry battalions, 9 machine gun companies (54 machine guns), 8 cavalry squadrons, 24 field artillery batteries (144 guns), 4 heavy artillery batteries (16 guns), 3 pioneer companies, and an aviation detachment.

Combat chronicle

On mobilisation, XXI Corps was assigned to the predominately Bavarian 6th Army forming part of the left wing of the forces for the Schlieffen Plan offensive in August 1914 on the Western Front. By 1915 it was on the Eastern Front where it took part in the siege of Kovno and the battles on the Neman River and at Vilnius. It was still in existence at the end of the war[14] in the 5th Army, Heeresgruppe Gallwitz on the Western Front.[15]


The XXI Corps had the following commanders during its existence:[16][17]

Dates Rank Name
1 October 1912 to 4 April 1915 General der Infanterie Fritz von Below
4 April 1915 to 2 January 1917 Generalleutnant Oskar von Hutier
2 January 1917 to end of war Generalleutnant Ernst von Oven

See also


  1. German Administrative History Accessed: 9 April 2012
  2. The Prussian Machine Accessed: 9 April 2012
  3. Cron 2002, p. 395
  4. Cron 2002, pp. 88–89
  5. Ellis & Cox 1993, pp. 186–187
  6. Haythornthwaite 1996, pp. 193–194
  7. They formed the Guards Cavalry Division, the only peacetime cavalry division in the German Army.
  8. War Office 1918, p. 260
  9. Had a third (Horse Artillery) Abteilung of three batteries of 4 guns.
  10. Had a third (Horse Artillery) Abteilung of three batteries of 4 guns.
  11. Cron 2002, p. 300
  12. Cron 2002, pp. 317–318
  13. 4 heavy artillery batteries (16 heavy field howitzers)
  14. Cron 2002, pp. 88–89
  15. Ellis & Cox 1993, pp. 186–187
  16. German Administrative History Accessed: 9 April 2012
  17. German War History Accessed: 9 April 2012


  • Cron, Hermann (2002). Imperial German Army 1914-18: Organisation, Structure, Orders-of-Battle [first published: 1937]. Helion & Co. ISBN 1-874622-70-1. 
  • Ellis, John; Cox, Michael (1993). The World War I Databook. Aurum Press Ltd. ISBN 1-85410-766-6. 
  • Haythornthwaite, Philip J. (1996). The World War One Source Book. Arms and Armour. ISBN 1-85409-351-7. 
  • 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. ISBN 0-948130-87-3. 
  • 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. ISBN 1-870423-95-X. 

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