=Reply with Artillery Fire.= The only means to decrease the effectiveness of the hostile bombardment is to reply with your own artillery. For this purpose, a certain part of your artillery is detailed for counter-battery work. The emplacements or approximate locations of the hostile guns are set down on maps. These are divided amongst the counter-battery artillery who attempt to silence or neutralize the same. In a sector, the commander may ask for what is known as counter-preparation fire. This fire is similar to the preliminary bombardment of the enemy. It covers the entire position of the enemy and is just as methodical in its scope. All the artillery that is at the disposal of the general is used for this purpose, and consequently the call for this fire must be through the general. Similar to the counter-preparation fire, but on a smaller scale, is what is known as preventive fire which may be called for from the support artillery. This fire covers the first and second lines and is used to prevent the enemy from assembling his troops in the first line for the assault. This fire has been found very efficient. It is called for by telephone and not automatically by rocket. II. Defense of the First Line during a Hostile Attack =Duties of Watchers.= At the moment the assault is launched, part of the enemy’s artillery establishes a barrage on your first line. The rest of the artillery, however, continues the regular bombardment to deceive the defenders as to the exact time of launching the attack. Therefore, the exact moment that the enemy comes over the top can only be determined by the watchers in your first line. It is their duty to give the alarm so that the garrison can reach its place in the firing line before the enemy reaches the same. This is a matter of seconds and not of minutes. Consequently, each dugout has a watcher located at its entrance and machine gun dugouts maintain special watchers. For each watcher at an entrance there is a second watcher within sight and calling distance ready to receive the alarm from the firing trench. If the second watcher is killed, the watcher at the entrance moves up and takes his place while another man from the dugout goes on watch there. These men are on duty only from fifteen to thirty minutes at a time. By a system of relief each occupant of a dugout serves a tour of duty as a watcher. The post of the watcher is protected as far as possible. [Illustration: POSITION OF WATCHERS]