On mobilisation, II Corps was assigned to the 1st Army, which was on the right wing of the forces for the Schlieffen Plan offensive in August 1914 on the Western Front. It saw action in the invasion of Belgium (Battle of Mons), the First Battle of the Marne, and the Race to the Sea (culminating in the First Battle of Ypres as part of the 6th Army). Thereafter, the Corps was transferred to the Eastern Front, joining the 9th Army. The Corps headquarters was upgraded to form the headquarters of the South Army on 10 January 1915.
