The 21st Reserve Division (21. Reserve-Division) was a unit of the Imperial German

German Empire

The German Empire refers to Germany during the "Second Reich" period from the unification of Germany and proclamation of Wilhelm I as German Emperor on 18 January 1871, to 1918, when it became a federal republic after defeat in World War I and the abdication of the Emperor, Wilhelm II.The German...

 Army

German Army (German Empire)

The German Army was the name given the combined land forces of the German Empire, also known as the National Army , Imperial Army or Imperial German Army. The term "Deutsches Heer" is also used for the modern German Army, the land component of the German Bundeswehr...

 in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The division was formed on mobilization of the German Army in August 1914. The division was disbanded in 1919 during the demobilization of the German Army after World War I. The division was raised primarily in the Prussian Province of Hesse-Nassau

Province of Hesse-Nassau

Hesse-Nassau Province was a province of the Kingdom of Prussia from 1868-1918, then a province of the Free State of Prussia until 1944.Hesse-Nassau was created as a consequence of the Austro-Prussian War of 1866 by combining the previously independent Hesse-Kassel , the Duchy of Nassau, the Free...

, but one battalion of the 88th Reserve Infantry Regiment came from the Grand Duchy of Hesse

Grand Duchy of Hesse

The Grand Duchy of Hesse and by Rhine , or, between 1806 and 1816, Grand Duchy of Hesse —as it was also known after 1816—was a member state of the German Confederation from 1806, when the Landgraviate of Hesse-Darmstadt was elevated to a Grand Duchy, until 1918, when all the German...

 and some other troops of the division came from Westphalia and the Rhine Province

Rhine Province

The Rhine Province , also known as Rhenish Prussia or synonymous to the Rhineland , was the westernmost province of the Kingdom of Prussia and the Free State of Prussia, within the German Reich, from 1822-1946. It was created from the provinces of the Lower Rhine and Jülich-Cleves-Berg...

.

Combat chronicle

The 21st Reserve Division fought on the Western Front

Western Front (World War I)

Following the outbreak of World War I in 1914, the German Army opened the Western Front by first invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The tide of the advance was dramatically turned with the Battle of the Marne...

, participating in the opening German offensive which led to the Allied Great Retreat

Great Retreat

The Great Retreat, also known as the Retreat from Mons, is the name given to the long, fighting retreat by Allied forces to the River Marne, on the Western Front early in World War I, after their holding action against the Imperial German Armies at the Battle of Mons on 23 August 1914...

 and ended with the First Battle of the Marne

First Battle of the Marne

The Battle of the Marne was a First World War battle fought between 5 and 12 September 1914. It resulted in an Allied victory against the German Army under Chief of Staff Helmuth von Moltke the Younger. The battle effectively ended the month long German offensive that opened the war and had...

. Thereafter, the division remained in the line in the Champagne region until June 1916. In July 1916, the division entered the Battle of Verdun

Battle of Verdun

The Battle of Verdun was one of the major battles during the First World War on the Western Front. It was fought between the German and French armies, from 21 February – 18 December 1916, on hilly terrain north of the city of Verdun-sur-Meuse in north-eastern France...

. It returned to the Champagne in September and then went back to Verdun in December 1916-January 1917. In the Spring of 1917, the division fought in the Second Battle of the Aisne

Second Battle of the Aisne

The Second Battle of the Aisne , was the massive main assault of the French military's Nivelle Offensive or Chemin des Dames Offensive in 1917 during World War I....

, also known as the Third Battle of Champagne. In November 1917, the division saw action in the tank battle at Cambrai. The division participated in the 1918 German Spring Offensive

Spring Offensive

The 1918 Spring Offensive or Kaiserschlacht , also known as the Ludendorff Offensive, was a series of German attacks along the Western Front during World War I, beginning on 21 March 1918, which marked the deepest advances by either side since 1914...

. It faced the Allied Hundred Days Offensive

Hundred Days Offensive

The Hundred Days Offensive was the final period of the First World War, during which the Allies launched a series of offensives against the Central Powers on the Western Front from 8 August to 11 November 1918, beginning with the Battle of Amiens. The offensive forced the German armies to retreat...

, and fought in the Second Battle of the Somme (1918)

Second Battle of the Somme (1918)

During the First World War, the Second Battle of the Somme of 1918 was fought on the Western Front from the end of the summer, in the basin of the Somme River...

 (also called the Third Battle of the Somme). Allied intelligence rated the division as second class.

Order of battle on mobilization

The order of battle of the 21st Reserve Division on mobilization was as follows:

• 41. Reserve-Infanterie-Brigade
  • Reserve-Infanterie-Regiment Nr. 80
  • Reserve-Infanterie-Regiment Nr. 87
• 42. Reserve-Infanterie-Brigade
  • Reserve-Infanterie-Regiment Nr. 81
  • Reserve-Infanterie-Regiment Nr. 88
• Reserve-Dragoner-Regiment Nr. 7
• Reserve-Feldartillerie-Regiment Nr. 21
• 4.Kompanie/Kurhessisches Pionier-Bataillon Nr. 11

Order of battle on March 8, 1918

The 21st Reserve Division was triangularized

Triangular division

A triangular division is a designation given to the way divisions are organized. In a triangular organization, the division's main body is composed of three regimental maneuver elements. These regiments may be controlled by a brigade headquarters or directly subordinated to the division commander...

in October 1916. Over the course of the war, other changes took place, including the formation of artillery and signals commands and a pioneer battalion. The order of battle on March 8, 1918 was as follows:

• 41. Reserve-Infanterie-Brigade
  • Reserve-Infanterie-Regiment Nr. 80
  • Reserve-Infanterie-Regiment Nr. 87
  • Reserve-Infanterie-Regiment Nr. 88
• 3.Eskadron/Reserve-Dragoner-Regiment Nr. 4
• Artillerie-Kommandeur 126
  • Reserve-Feldartillerie-Regiment Nr. 21
  • Kgl. Bayerisches Fußartillerie-Bataillon Nr. 22
• Stab Pionier-Bataillon Nr. 321
  • 4.Kompanie/Kurhessisches Pionier-Bataillon Nr. 11
  • 5.Kompanie/Kurhessisches Pionier-Bataillon Nr. 11
  • Minenwerfer-Kompanie Nr. 221
• Divisions-Nachrichten-Kommandeur 421