Rifle, A. M. R., and grenade fire from the first line will usually stop a surprise attack. But since it is impossible to ascertain the strength of the attacking troops, the defensive artillery barrage is called for. Similarly, the reserve troops located in the cover and support trenches may be used for the purposes of reinforcement and counterattacks, depending upon the success of the enemy’s attack. The captain of a support point must not only keep up the offensive spirit of his garrison by all the means of trench fighting, but he must organize and maintain a vigilant guard and patrol service for security. Attack in Force Attacks in force are carried out to capture an important position, or there may be a series of such objectives along a front in a general offensive. On the other hand, the object of the defense is not only to repulse the enemy but also to inflict upon him as great a loss as possible. The phases of a great attack are: the preparation, of which the final and most important element is the bombardment; the assault of the first line; and the exploitation of success by fighting in the interior of the position. The defending troops must combat each one of these phases by the most adequate measures. We shall take up these measures in detail. I. During the Preparation of the Hostile Attack =Revealing Symptoms of the Attack.= The preparation of the hostile attack reveals itself by different preparations: (1) The activity of the enemy: His infantry will send out more numerous and aggressive patrols and reconnaissance parties. His artillery will increase its daily destructive fire. It will multiply its number of registering shots, establish barrage fires in the interior of your position, and begin to concentrate on communication routes. His air service will take on unusual activities. (2) Vigilant observation of roads and territory behind the enemy’s lines may reveal convoys carrying troops and supplies, the assembling of troops in woods, etc. (smoke from their kitchens), accumulation of materials in depots (often accompanied by explosions in artillery dumps). (3) The observation service may discover new hostile works, such as the contraction of parallels of departure out in front of his first line. There may be also successive parallels behind the nearest jumping-off trench. (4) Prisoners and deserters, who become more numerous because of the approaching offensive, may give valuable information concerning the coming attack. The task of discovering the enemy’s preparation for an attack is incumbent upon all ranks, but above all, this duty devolves particularly upon the information service, balloon and air service, and artillery observers. In the sector, the intelligence officer must perfect his system of observation to the highest degree. The information in the daily reports is carefully sorted and tested.