# XVIII Corps (German Empire)

The XVIII Army Corps / XVIII AK (German: XVIII. 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, the XVIII Army Corps was set up on 1 April 1899 in Frankfurt am Main as the Generalkommando (headquarters) for the district of Wiesbaden and the Grand Duchy of Hesse. It took over command of 21st Division from XI Corps and the previously separate 25th (Grand Ducal Hessian) Division. It was assigned to the VII Army Inspectorate, but joined the 4th Army at the start of the First World War.
It was still in existence at the end of the war, serving in the 17th Army, Heeresgruppe Kronprinz Rupprecht on the Western Front.

## 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. 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 Corps 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).
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
Peacetime organization of the Corps :
| Corps | Division | Brigade | Units | Garrison |
| XVIII Corps | 21st Division | 41st Infantry Brigade | 87th (1st Nassau) Infantry | Mainz |
| XVIII Corps | 21st Division | 41st Infantry Brigade | 88th (2nd Nassau) Infantry | Mainz, II Bn at Hanau |
| XVIII Corps | 21st Division | 42nd Infantry Brigade | 80th (Kurhessian) Fusiliers "von Gersdorff" | Wiesbaden, II Bn at Bad Homburg |
| XVIII Corps | 21st Division | 42nd Infantry Brigade | 81st (1st Kurhessian) Infantry "Landgrave Frederick I of Hesse-Cassel" | Frankfurt am Main |
| XVIII Corps | 21st Division | 21st Field Artillery Brigade | 27th (1st Nassau) Field Artillery "Oranien" | Mainz, Wiesbaden |
| XVIII Corps | 21st Division | 21st Field Artillery Brigade | 63rd (2nd Nassau) Field Artillery | Frankfurt am Main |
| XVIII Corps | 21st Division | 21st Cavalry Brigade | 6th (Magdeburg) Dragoons | Mainz |
| XVIII Corps | 21st Division | 21st Cavalry Brigade | 6th (Thuringian) Uhlans | Hanau |
| XVIII Corps | 25th Division | 49th Infantry Brigade | 115th (1st Grand Ducal Hessian) Lifeguard Infantry | Darmstadt |
| XVIII Corps | 25th Division | 49th Infantry Brigade | 116th (2nd Grand Ducal Hessian) Infantry "Emperor William" | Gießen |
| XVIII Corps | 25th Division | 49th Infantry Brigade | 168th (5th Grand Ducal Hessian) Infantry | Offenbach, I Bn at Butzbach, III Bn at Friedberg |
| XVIII Corps | 25th Division | 50th Infantry Brigade | 117th (3rd Grand Ducal Hessian) Life Infantry "Grand Duchess" | Mainz |
| XVIII Corps | 25th Division | 50th Infantry Brigade | 118th (4th Grand Ducal Hessian) Infantry "Prince Charles" | Worms |
| XVIII Corps | 25th Division | 25th Field Artillery Brigade | 25th (1st Grand Ducal Hessian) Field Artillery | Darmstadt |
| XVIII Corps | 25th Division | 25th Field Artillery Brigade | 61st (2nd Grand Ducal Hessian) Field Artillery | Darmstadt, Babenhausen |
| XVIII Corps | 25th Division | 25th Cavalry Brigade | 23rd Guards Dragoons (1st Grand Ducal Hessian) | Darmstadt |
| XVIII Corps | 25th Division | 25th Cavalry Brigade | 24th Life Dragoons (2nd Grand Ducal Hessian) | Darmstadt |
| XVIII Corps | Corps Troops | | 8th Fortress Machine Gun Abteilung | Mainz |
| XVIII Corps | Corps Troops | | 3rd (General-Feldzeugmeister) (Brandenburg) Foot Artillery | Mainz |
| XVIII Corps | Corps Troops | | 21st (1st Nassau) Pioneer Battalion | Mainz |
| XVIII Corps | Corps Troops | | 25th (2nd Nassau) (Fortress-)Pioneer Battalion | Mainz |
| XVIII Corps | Corps Troops | | 7th (Royal Saxon) (Fortress-) Telephone Company | Mainz |
| XVIII Corps | Corps Troops | | 18th (Grand Ducal Hessian) Train Battalion | Darmstadt |
| XVIII Corps | Corps Troops | | 2nd Railway Regiment | Hanau |
| XVIII Corps | Corps Troops | | 3rd Railway Regiment | Hanau |

## World War I
### Organisation on mobilisation

On mobilization, on 2 August 1914, the Corps was restructured. The 25th Cavalry Brigade was withdrawn to form part of the 3rd Cavalry Division and the 21st Cavalry Brigade was broken up and its regiments assigned to the divisions as reconnaissance units. The 168th Infantry Regiment was assigned to the 25th Reserve Division in XVIII Reserve Corps. Divisions received engineer companies and other support units from the Corps headquarters. In summary, XVIII 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.
Initial wartime organization of the Corps :
| Corps | Division | Brigade | Units |
| XVIII Corps | 21st Division | 41st Infantry Brigade | 87th Infantry Regiment |
| XVIII Corps | 21st Division | 41st Infantry Brigade | 88th Infantry Regiment |
| XVIII Corps | 21st Division | 42nd Infantry Brigade | 80th Fusilier Regiment |
| XVIII Corps | 21st Division | 42nd Infantry Brigade | 81st Infantry Regiment |
| XVIII Corps | 21st Division | 21st Field Artillery Brigade | 27th Field Artillery Regiment |
| XVIII Corps | 21st Division | 21st Field Artillery Brigade | 63rd Field Artillery Regiment |
| XVIII Corps | 21st Division | | 6th Uhlan Regiment |
| XVIII Corps | 21st Division | | 1st Company, 21st Pioneer Battalion |
| XVIII Corps | 21st Division | | 21st Divisional Pontoon Train |
| XVIII Corps | 21st Division | | 1st Medical Company |
| XVIII Corps | 21st Division | | 3rd Medical Company |
| XVIII Corps | 25th Division | 49th Infantry Brigade | 115th Life Guard Infantry Regiment |
| XVIII Corps | 25th Division | 49th Infantry Brigade | 116th Infantry Regiment |
| XVIII Corps | 25th Division | 50th Infantry Brigade | 117th Life Infantry Regiment |
| XVIII Corps | 25th Division | 50th Infantry Brigade | 118th Infantry Regiment |
| XVIII Corps | 25th Division | 25th Field Artillery Brigade | 25th Field Artillery Regiment |
| XVIII Corps | 25th Division | 25th Field Artillery Brigade | 61st Field Artillery Regiment |
| XVIII Corps | 25th Division | | 6th Dragoon Regiment |
| XVIII Corps | 25th Division | | 2nd Company, 21st Pioneer Battalion |
| XVIII Corps | 25th Division | | 3rd Company, 21st Pioneer Battalion |
| XVIII Corps | 25th Division | | 25th Divisional Pontoon Train |
| XVIII Corps | 25th Division | | 2nd Medical Company |
| XVIII Corps | Corps Troops | | I Battalion, 3rd Foot Artillery Regiment |
| XVIII Corps | Corps Troops | | 27th Aviation Detachment |
| XVIII Corps | Corps Troops | | 18th Corps Pontoon Train |
| XVIII Corps | Corps Troops | | 18th Telephone Detachment |
| XVIII Corps | Corps Troops | | 21st Pioneer Searchlight Section |
| XVIII Corps | Corps Troops | | Munition Trains and Columns corresponding to II Corps |

### Combat chronicle

On mobilisation, XVIII Corps was assigned to the 4th Army forming part of the centre of the forces for the Schlieffen Plan offensive in August 1914. It was still in existence at the end of the war, serving in the 17th Army, Heeresgruppe Kronprinz Rupprecht on the Western Front.

## Commanders

The XVIII Corps had the following commanders during its existence:
| Dates | Rank | Name |
| 25 March 1899 to 30 April 1904 | General der Infanterie | Oskar von Lindequist |
| 1 May 1904 to 12 September 1912 | Generalleutnant | Hermann von Eichhorn |
| 13 September 1912 to 20 January 1917 | General der Infanterie | Dedo von Schenck |
| 21 January 1917 to 26 August 1918 | Generalleutnant | Viktor Albrecht |
| 27 August 1918 to end of the war | Generalleutnant | Günther von Etzel |