In order to silence the hostile artillery, it seems that, knowing the probable emplacement of the batteries, it would be necessary suddenly and without warning to let loose on them a deluge of fire. The personnel of these batteries not being continually at their firing positions, this sudden tempest would surprise them and keep them inside their shelters. In the midst of the confusion, the fire of the batteries which try to get into action is much disturbed, impeded, and frequently interrupted. On the 9th of May, the hostile artillery must have been completely surprised and literally stupefied during the whole morning, for they abandoned their infantry. Only a few pieces fired some hasty shots. In order to render the emplacements of the batteries completely untenable, they might be overwhelmed with shells giving off clouds of smoke and also asphyxiating shells; by this means the cannoneers would be obliged to quit their pieces or serve them under extremely difficult conditions. The aviators hovering over the hostile lines could complete the preparation by indicating by means of luminous balls to the batteries on watch the hostile batteries not yet silenced or which have come into action. (_d_) _Preparation against Reinforcements and Reserves._ In the second and third trenches, the garrison does not generally occupy its firing positions; it is obliged to get to them in case of attack. As long as the artillery preparation lasts, it does not budge from the shelters; but as soon as the artillery ceases its fire, the garrison hastily mans the positions. It is necessary then for the artillery to extend its fire to the second and third lines and to continue this fire while the infantry rushes the first line. The approach trenches and their junctions should especially be swept. This has, moreover, the advantage of keeping crouched in their holes the defenders of the first line, who are not reassured by sensing the compact sheaves of the terrible explosive passing close over their heads. The preparation on the second line of defense is absolutely identical. It is next necessary to cut the battlefield in two and isolate the zone of the first and second lines of defence, constantly manned by the troops near their combat positions, from the zone of cantonment. It is a matter of establishing an insuperable barrier. A barrier solely of ordinary shell fire is extremely expensive. The Germans have more simply solved the question by establishing a barrier of asphyxiating gas. They have employed this extremely effective scheme, it seems, at Bagatelle in the Argonne, on the 30th of June and the 1st and 2d of July.