The British 20th (Light) Division was a New Armydivision formed in September 1914 as part of the K2 Army Group. The division landed in France July 1915 and spent the duration of the First World War in action on the Western Front.
The assault was assigned to the 19 divisions of the British Third Army; of these no fewer than fourteen were still recovering from the slaughter at Third Ypres.
The divisions of the British III and IV Corps were to lead the attack.
The Germans had put two divisions of Gruppe Arras on the ridge with another two in reserve, Gruppe Caudry was reinforced and to challenge the RFC the squadrons under the von Richthofen were assigned.