The 1st Reserve Division (1. Reserve-Division) was a reserve infantry division of the Imperial German Army in World War I. It was formed, on mobilization in August 1914, from reserve infantry units, primarily from East Prussia, and was part of I Reserve Corps. The division served on the Eastern Front from the beginning of the war until October 1917, after which it was transferred to the Western Front 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.