(xiv) Special arrangements will be made by corps for warning the civil authorities who are responsible for the protection and warning of all civilians within the corps area.
21. ACTION AFTER ENEMY GAS ATTACK.—(i) Smoking will be prohibited for a period of three hours after the gas has ceased.
(ii) After a gas attack troops in the front trenches will be relieved of all fatigue and carrying work for 24 hours by sending up working parties from companies in rear. Horses should not be worked for a similar period if it can be avoided.
(iii) No man suffering from effects of gas will be permitted to walk to the dressing station.
(iv) Rifles and machine guns should be cleaned immediately after a gas attack; oil cleaning will prevent corrosion for 12 hours, but the first available opportunity should be taken to clean all parts in boiling water containing a little soda.
22. ACTION DURING GAS SHELL BOMBARDMENT.—(i) Small box respirators will be put on in the shelled area.
(ii) In the event of a sudden and intense bombardment with gas shell a local alarm will be given in the front-line system of trenches by orderlies; in reserve trenches and battery positions this local alarm may be given by French shunters' horns. In order to avoid false alarms of a gas attack the French shunters' horns should not be used in Infantry front-line trenches.
(iii) All dugouts in the vicinity will be visited and any sleeping men aroused.
23. DISCIPLINE WITH REGARD TO CARRYING SMALL BOX RESPIRATORS.—Small box respirators will always be carried within 2 miles of the front line (i.e., in advance of the line Elverdinghe—Vlamertinghe—Dickebush—Kemmel Hill—Neuve Eglise—Nieppe—Laventie) whatever the direction of the wind is. P. H. helmets will always be carried in corps areas whatever the direction of the wind is.
"WIND-DANGEROUS" period.—Orders as to the position in which the above are worn in "wind-dangerous" period are contained in section 19.