Let us consider a concrete example where the enemy is about to explode a mine under your first line of trenches (examine accompanying diagram, Precautions against a Mine). When it has been definitely discovered that the enemy has a mine gallery under your first line and there is no means of combating it by countermining, etc., the infantry in the position must take certain precautions. By listening devices the powder chamber is located. The extent of the crater is also calculated. A new first line is constructed behind, excluding the mine crater and at a distance of about 30 yards from its lip. This re-entrant angle of the first line is made by using boyaux on the flank if they exist. A cover trench is also constructed behind this first line. The infantry moves back to this new line behind the threatened area of explosion. Every other defensive precaution is taken against the explosion and the accompanying assault of the enemy. Heavy bombing posts are located on the flanks of the crater. The position of these posts is usually at the point of change of direction of the old firing line with the new one of the re-entrant angle. Dugouts may be constructed close to these bombing posts for the protection of the grenadiers during the explosion. Immediately the explosion is over, these grenadiers man their posts and establish a heavy barricade between the posts and the crater by using hand grenades. If the enemy attempts to enter the crater, these grenadiers can make it untenable by throwing hand grenades into it. Automatic rifle or machine gun emplacements are also located on both flanks of the crater. Their function is to establish flanking fire on hostile troops attempting to approach the crater. Rifle grenadiers are stationed in the line of trenches to establish a defensive rifle barrage out in front of the crater. The riflemen will usually occupy the near and flank lips of the crater. They will not occupy the lip of the crater nearest the enemy until it is ascertained that the enemy has no more galleries. A rocket post is located in the first line on the flanks of the crater. As soon as the crater is exploded, a rocket is sent up from this post calling upon the artillery for a defensive barrage. Usually, special artillery is detailed for this extra fire. It is a reinforced fire, or a combination of preventive fire and protective barrage. It is established on the enemy’s first line rather than in “No Man’s Land” as a purely defensive barrage. With all these precautions taken, the infantry await the explosion of the mine. _A Selection from the Catalogue of_ G. P. PUTNAM’S SONS ❧ Complete Catalogue sent on application IT IS THE REAL STUFF OVER THE TOP BY AN AMERICAN SOLDIER WHO WENT ARTHUR GUY EMPEY