21st Infantry Division in World War I
1914 The Division fought in the Allied Great Retreat, including the First Battle of the Marne, and in the Race to the Sea.
The Great Retreat is the name given to the slow, 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. The Allies were closely pursued by the Germans, acting under the Schlieffen Plan.
1915 Involved in the static trench warfare and engagements that evolved by mid-1915
1916 The Division saw action in the Battle of Verdun and the Battle of the Somme.
1917 Fought in the Second Battle of the Aisne.
1918 The Division served in the German 1918 Spring Offensive, including the Second Battle of the Somme. The 1918 Spring Offensive or Kaiserschlacht (Kaiser's Battle), also known as the Ludendorff Offensive, was a series of German attacks along the Western Front during World War I, which marked the deepest advances by either side since 1914. The German authorities had realised that their only remaining chance of victory was to defeat the Allies before the overwhelming human and matériel resources of the United States could be deployed. They also had the advantage of nearly 50 divisions freed by the Russian surrender (Treaty of Brest-Litovsk).
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, and in the city of Frankfurt am Main and was rated by Allied intelligence as a first class unit. The Division was disbanded in 1919 during the demobilization of the German Army after World War I.
On mobilization in August 1914 most divisional cavalry, including brigade headquarters, was withdrawn to form cavalry divisions or split up among divisions as reconnaissance units.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:
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 - one infantry brigade with three infantry regiments rather than two infantry brigades of two regiments (a "square 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: