The 1st Reserve Division (1. Reserve-Division) was a reserve infantry division of the Imperial 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...

. It was formed on mobilization in August 1914 from reserve infantry units primarily from East Prussia

East Prussia

East Prussia is the main part of the region of Prussia along the southeastern Baltic Coast from the 13th century to the end of World War II in May 1945. From 1772–1829 and 1878–1945, the Province of East Prussia was part of the German state of Prussia. The capital city was Königsberg.East Prussia...

. The division served from the beginning of the war until October 1917 on the Eastern Front

Eastern Front (World War I)

The Eastern Front was a theatre of war during World War I in Central and, primarily, Eastern Europe. The term is in contrast to the Western Front. Despite the geographical separation, the events in the two theatres strongly influenced each other...

, after which it was transferred to 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...

 for the war's final campaigns. It was rated a third class division by Allied intelligence, mainly due to its losses in heavy fighting and reduced quality of replacement troops.

August 1914 organization

The 1st Reserve Division's initial wartime organization was as follows:

• 1.Reserve-Infanterie-Brigade:
  • Reserve-Infanterie-Regiment Nr. 1
  • Reserve-Infanterie-Regiment Nr. 3
• 72.Reserve-Infanterie-Brigade:
  • Reserve-Infanterie-Regiment Nr. 18
  • Reserve-Infanterie-Regiment Nr. 59
  • Reserve-Jäger-Bataillon Nr. 1
• Reserve-Ulanen-Regiment Nr. 1
• Reserve-Feldartillerie-Regiment Nr. 1
• 4./Pommersches Pionier-Bataillon Nr. 2

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...

"). The 1st Reserve Division triangularized in June 1917. 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 1st Reserve Division's order of battle on January 1, 1918 was as follows:

• 1.Reserve-Infanterie-Brigade:
  • Ostpreußisches Reserve-Infanterie-Regiment Nr. 1
  • Ostpreußisches Reserve-Infanterie-Regiment Nr. 3
  • Posensches Reserve-Infanterie-Regiment Nr. 59
• 4.Eskadron/2.Garde-Ulanen-Regiment
• Artillerie-Kommandeur 71:
  • Reserve-Feldartillerie-Regiment Nr. 1
  • II./Reserve-Fußartillerie-Regiment Nr. 1
• Stab Pionier-Bataillon Nr. 301:
  • 4./Pommersches Pionier-Bataillon Nr. 2
  • 1.Reserve-Kompanie/Pionier-Bataillon Nr. 34
  • Minenwerfer-Kompanie Nr. 201
• Divisions-Nachrichten-Kommandeur 401