period was an experimental one, but we know that by August, 1915, German military opinion had crystallised out to the extent of formulating certain rules, issued as Falkenhayn's orders for the employment of gas shell. These early orders defined two types of shell, one persistent, for harassing purposes, and the other non-persistent, to be used immediately before an attack. They specified the number of shell to be used for a given task. But in this they were unsound and it is clear that the Germans had an exaggerated opinion of what could be achieved with a small number of shell. They adhered too closely to high explosive practice. Various documents reveal the fact that the Germans were much more satisfied with their gas tactics than they would have been had they possessed information with regard to our losses from their shell. They attached insufficient importance to the value of surprise and highly concentrated shoots, and had a mistaken idea of the actual specific aggressive value of their early types.

Lachrymators at Loos, 1915.—Germany commenced the manufacture of lachrymators, crude brominated xylene or brominated ketones, early in, or perhaps before 1915. These substances caused great inconvenience through temporary blindness by lachrymation, but were not highly toxic. In June, 1915, however, they began to produce lethal gas for shell. Falkenhayn's orders for the use of gas shell, mentioned above, although they represent by no means the best final practice, were definite evidence that gas had come to stay with the Germans. The writer has vivid recollections of their use of lachrymators in the Loos Battle. Batteries in the open, under the crest near the Lens road, were in position so that the wind direction practically enfiladed them, sweeping along from the direction of Le Rutoire farm. Gas from German shell, borne on the wind, was continually enveloping the line of batteries, but they remained in action. It was on this occasion while watching the bursting gas shells from the outskirts of the mining village of Philosophe that Major-General Wing was killed outright by a high explosive shell. These gas shells certainly did not achieve the results which the Germans expected, although they were not without effect. Demolished villages, the only shelter for troops in a desolate area, have been rendered uninhabitable for days by a concentrated lachrymator enemy shoot of less than one hour. Again, walking into gas "pockets" up a trench one has been stopped as by a fierce blow across the eyes, the lachrymatory effect was so piercing and sudden. The great inconvenience which was occasioned to parties engaged in the routine of trench warfare, on ration or engineering duties, and the effect on movement in the rear after an assault, taken cumulatively, represented a big military factor.