The first wave of the support is usually formed of the one-half section of specialists. The echeloning of the specialists in front is also the most favorable formation to progress by rushes in a terrain cut up by shell holes. The chief of section is between the two (2) waves of his section. The captain is usually in front of the support sections. The support sections are closely followed by a powerful line of machine guns, which are thrown into the fight when needed to reenforce the leading units. "Trench Cleaners" usually march immediately after the leading sections and may be taken from the support sections. They are armed with pistols, knives and hand grenades. The captain can use his section complete, or take out the specialists and use them for a particular purpose. The specialists carry only the weapons of their specialty and have their loads lightened. The ordinary riflemen carry the usual packs and equipment. Officers no longer lead the assault, but direct it. They are equipped with the rifle and bayonet, the same as the enlisted man. Each unit of the first wave of the attack is given a definite objective. Different waves must not break upon the first wave. Fire is opened by the assaulting troops only at short ranges, the advance being protected by a curtain of artillery fire. The advancing line makes use of shell holes and all other available cover. When the first section reaches its objective it is joined by the half section of riflemen; it immediately organizes the captured ground. Attacking From Trenches.--The commanders of brigades and battalions, with the commander of the artillery detailed to support them, study on the ground the artillery plan so far as it affects them. Immediately after the advance of the infantry begins, the artillery supporting it commences an intense bombardment with the object of forcing the enemy to take cover. At the moment laid down in the table of artillery fire the barrage lifts clear of the trench and the infantry rush in and capture it. The infantry must be taught that their success depends upon their getting within 75 yards of the barrage before it lifts, in order that they may reach the trenches before the enemy can man them. The secret of a successful assault is exact synchronization of the movements of the infantry with those of the barrage. The pace of a barrage depends, to a certain extent, on the pace of the infantry, which varies with the condition of the ground, the length of the advance, the number of enemy trenches to be crossed, etc. It may be from 15 to 75 yards per minute. The pace of the barrage should be quicker at first, and should gradually slow down as the men become exhausted, in order to give them time to get close to the barrage and pull themselves together for the final rush.