(a) The Front System—an outpost system, including its own supports.

(b) A Supporting System, known as the “Purple System,” on the ridge Monchy-au-Bois—Fonquevillers—Gommecourt—Colincamps. This system must be held against all attacks.

(c) The Sailly-au-Bois—Château de la Haie Switch between the Purple and Red Systems.

(d) A Reserve System—known as the “Red Line”—forming the line of assembly of the divisions in Corps Reserve in case of attack.

Infantry brigades were responsible for the defence of their respective sections of the Front and Purple Systems and all intervening ground, and for the organization, construction, and upkeep of all defences. In each system, or zone, mutually supporting localities were held, with each locality its own commander, even down to platoons. Localities were so selected as to defend tactical points, and, as far as possible, were arranged chequer-wise in depth. If the troops on a flank were wiped out or overrun a defensive flank was to be formed from the supports. The artillery were also distributed in depth so that some batteries were available in each zone. Battery positions were fortified, and were to be defended to the last. The R.A. had been instructed in the use of the “hand gun,” as the gunners derisively termed the rifle. The machine-gun defence was most carefully and skilfully organized, also in depth, and in no zone were there any covered approaches which could not be swept by machine-gun fire.

Divisional Engineers and Pioneers were allotted to the Brigades as follows—

The Field Companies and Pioneers were placed under the orders of Brigade Commanders, the C.R.E. to assist Brigade Commanders as much as possible and to supervise the work of the Field Companies and Pioneer Battalion. The divisional front was covered by seven Brigades of Field Artillery and three Brigades of Garrison Artillery.

As the very severe weather continued the postponement of the expected enemy attack until more favourable conditions should prevail seemed probable. In view of this the Divisional Commander on April 19 ordered that every effort must be made to ensure both security and the comfort and welfare of the men. The instructions to this effect emphasized the importance of: the field of fire and flanking fire of defensive localities; fire-stepping trenches; improving communications; improving defence against gas, particularly the gas-proofing of deep dug-outs. As many men as possible were to be provided with shell-proof dug-out accommodation, and where this was impossible improvised weather shelters to be constructed. The provision of hot meals in forward areas, of dry standings to prevent “trench feet,” of a supply of clean socks and clothing, and of baths and drying-rooms in accessible positions. As much use as possible to be made of trench tramways to relieve the strain on transport and carrying parties. “There is so much necessary work to be done that man power and horse power must be conserved by making every use of available machinery.”