The 21st Division was a unit of the Prussia

Prussia

Prussia was a German kingdom and historic state originating out of the Duchy of Prussia and the Margraviate of Brandenburg. For centuries, the House of Hohenzollern ruled Prussia, successfully expanding its size by way of an unusually well-organized and effective army. Prussia shaped the history...

n/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...

. It was formed on October 11, 1866 and was headquartered in Frankfurt am Main. The division was subordinated in peacetime initially to the XI Army Corps (XI. Armeekorps) and from 1899 to the XVIII Army Corps

XVIII Corps (German Empire)

The XVIII Army Corps was a corps of the Imperial German Army. It was formed on April 1, 1899 and was headquartered in Frankfurt am Main...

 (XVIII. Armeekorps).

The division was recruited in the formerly independent Duchy of Nassau and the Electorate of Hesse, which had been incorporated into Prussia after the Austro-Prussian War

Austro-Prussian War

The Austro-Prussian War was a war fought in 1866 between the German Confederation under the leadership of the Austrian Empire and its German allies on one side and the Kingdom of Prussia with its German allies and Italy on the...

, and in the city of Frankfurt am Main.

The division was disbanded in 1919 during the demobilization of the German Army after 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...

.

Combat chronicle

During the Franco-Prussian War

Franco-Prussian War

The Franco-Prussian War or Franco-German War, often referred to in France as the 1870 War was a conflict between the Second French Empire and the Kingdom of Prussia. Prussia was aided by the North German Confederation, of which it was a member, and the South German states of Baden, Württemberg and...

, the 21st Infantry Division fought in the opening Battle of Woerth and the major Battle of Sedan

Battle of Sedan

The Battle of Sedan was fought during the Franco-Prussian War on 1 September 1870. It resulted in the capture of Emperor Napoleon III and large numbers of his troops and for all intents and purposes decided the war in favour of Prussia and its allies, though fighting continued under a new French...

. It subsequently participated in the Siege of Paris

Siege of Paris

The Siege of Paris, lasting from September 19, 1870 – January 28, 1871, and the consequent capture of the city by Prussian forces led to French defeat in the Franco-Prussian War and the establishment of the German Empire as well as the Paris Commune....

.

In World War I in 1914, the 20th Infantry Division fought in 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...

, including 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...

, and in the Race to the Sea

Race to the Sea

The Race to the Sea is a name given to the period early in the First World War when the two sides were still engaged in mobile warfare on the Western Front. With the German advance stalled at the First Battle of the Marne, the opponents continually attempted to outflank each other through...

. In 1916, it saw action in 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...

 and the Battle of the Somme. In 1917, it 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....

. It served in the German 1918 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...

, including the Second Battle of the Somme

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...

. Allied intelligence rated the division as first class.

Order of battle in the Franco-Prussian War

During wartime, the 21st Division, like other regular German divisions, was redesignated an infantry division. The organization of the 21st Infantry Division in 1870 at the beginning of the Franco-Prussian War was as follows:

• 41. Infanterie-Brigade
  • Füsilier-Regiment Nr. 34
  • Füsilier-Regiment Nr. 80
• 42. Infanterie-Brigade
  • Infanterie-Regiment Nr. 82
  • Infanterie-Regiment Nr. 88
• Jäger-Bataillon Nr. 11
• Dragoner-Regiment Nr. 5

Pre-World War I organization

German divisions underwent various organizational changes after the Franco-Prussian War. As noted above, the 21st Division was reorganized to become primarily a Hannover/Brunswick unit. The organization of the 21st Division in 1914, shortly before the outbreak of World War I, was as follows:

• 41. Infanterie-Brigade:
  • 1. Nassauisches Infanterie-Regiment Nr. 87
  • 2. Nassauisches Infanterie-Regiment Nr. 88
• 42.Infanterie-Brigade:
  • Füsilier-Regiment von Gerdsdorff (1. Kurhessisches) Nr. 80
  • Infanterie-Regiment Landgraf Friedrich I. von Hessen-Kassel (1. Kurhessisches) Nr. 81
• 21. Kavallerie-Brigade:
  • Magdeburgisches Dragoner-Regiment Nr. 6
  • Thüringisches Ulanen-Regiment Nr. 6
• 21. Feldartillerie-Brigade:
  • 1. Nassauisches Feldartillerie-Regiment Nr. 27
  • 2. Nassauisches Feldartillerie-Regiment Nr. 63

Order of battle on mobilization

On mobilization in August 1914 at the beginning of 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...

, most divisional cavalry, including brigade headquarters, was withdrawn to form cavalry divisions or split up among divisions as reconnaissance units. Divisions received engineer companies and other support units from their higher headquarters. The 21st Division was again renamed the 21st Infantry Division and its initial wartime organization was as follows:

• 41. Infanterie-Brigade:
  • 1. Nassauisches Infanterie-Regiment Nr. 87
  • 2. Nassauisches Infanterie-Regiment Nr. 88
• 42.Infanterie-Brigade:
  • Füsilier-Regiment von Gerdsdorff (1. Kurhessisches) Nr. 80
  • Infanterie-Regiment Landgraf Friedrich I. von Hessen-Kassel (1. Kurhessisches) Nr. 81
• Thüringisches Ulanen-Regiment Nr. 6
• 21. Feldartillerie-Brigade:
  • 1. Nassauisches Feldartillerie-Regiment Nr. 27
  • 2. Nassauisches Feldartillerie-Regiment Nr. 63
• 1.Kompanie/1. Nassauisches Pionier-Bataillon Nr. 21

Late World War I organization

Divisions underwent many changes during the war, with regiments moving from division to division, and some being destroyed and rebuilt. During the war, most divisions became triangular

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...

 - one infantry brigade with three infantry regiments rather than two infantry brigades of two regiments (a "square division

Square division

A square division is a designation given to the way military divisions are organized. In a square organization, the division's main body is composed of four regimental elements. Since a regiment could be split into separate battalions for tactical purposes, the natural division within a division...

"). An artillery commander replaced the artillery brigade headquarters, the cavalry was further reduced, the engineer contingent was increased, and a divisional signals command was created. The 21st Infantry Division's order of battle on April 28, 1918 was as follows:

• 42. Infanterie-Brigade:
  • Füsilier-Regiment von Gerdsdorff (1. Kurhessisches) Nr. 80
  • Infanterie-Regiment Landgraf Friedrich I. von Hessen-Kassel (1. Kurhessisches) Nr. 81
  • 1. Nassauisches Infanterie-Regiment Nr. 87
• 2.Eskadron/Magdeburgisches Dragoner-Regiment Nr. 6
• Artillerie-Kommandeur 21:
  • 1. Nassauisches Feldartillerie-Regiment Nr. 27
  • II.Bataillon/Badisches Fußartillerie-Regiment Nr. 14 (from May 7, 1918)
• Stab 1. Nassauisches Pionier-Bataillon Nr. 21:
  • 1.Kompanie/1. Nassauisches Pionier-Bataillon Nr. 21
  • 5.Kompanie/1. Nassauisches Pionier-Bataillon Nr. 21
  • Minenwerfer-Kompanie Nr. 21
• Divisions-Nachrichten-Kommandeur 21