1. The Mode Of Action.—The machine gun acting only by its fire can prepare an attack or repulse an offensive movement, but it does not conquer ground. The latter role is almost exclusively that of infantry which is fitted for crossing all obstacles. When it will suffice to act by fire, employ the machine gun in preference to infantry, preserving the latter for the combined action of movement and fire. By the employment of the machine gun economize infantry, reserving a more considerable portion of it for manoeuvre purposes.
  2. Fire.—Machine gun fire produces a sheath, dense, deep but narrow. The increase of the width of the sweeping fire gives to the sheath a greater breadth, but when the density becomes insufficient, the effect produced is very weak. Machine gun fire will have its maximum power upon an objective of narrow front and great depth. With the infantry fighting normally in thin lines the preceding conditions will generally only be realized when these lines are taken in the flank. "The fire of the machine gun parallel to the probable front of the enemy—a flanking fire—must therefore be the rule." The fire perpendicular to the front will be employed generally on certain necessary points of passage as, bridges, roads, defiles, cuts, roadways, communicating trenches, etc., where the enemy is generally forced to take a deep formation with a narrow front, or where he is in massed formation.
  3. Inconspicuousness.—By reason of its small strength the machine gun section can utilize the smallest cover, and can consequently hide from the enemy; the machine gun therefore, more than the infantry, has the chance to act by surprise. The opening of the fire by surprise will be the rule; the machine gun will avoid revealing itself upon objectives not worth the trouble. Flank action and surprise are the two conditions to try for under all circumstances.

2. Offensive Reinforcement Of A Front Momentarily Stationary.—The machine guns assisted by small elements of infantry cover thoroughly the getting in hand of the main body, the machine guns presenting to the enemy a line of little vulnerability. The machine guns assist in securing the possession of the ground previously taken, and will permit time to prepare for the resumption of the forward movement. Preparation of the attack—machine gun fire completes the preparation done by the artillery, either by acting on the personnel or by opening breaches in the accessary defenses. At times the machine guns alone may be charged with the preparation of the attack where it is necessary to act very quickly as in pursuit, exploitation of a success. Whatever the situation, concentrate the machine gun fire on one or several points. Machine guns cover the flanks of attacking troops. They follow the advance of these troops remaining on the flanks, so as to be able to fire instantly on all points from which an attack might come. Machine guns will likewise be employed in intervals created intentionally or accidentally between units. It is here a powerful weapon which can rapidly be put into action by the Commander. The personnel and material must be protected as far as possible from the effects of fire.

3. Defensive.—It is here that the flanking fire is especially necessary. In the defensive preparation of a position the machine guns must be so placed that they will provide along the front several successive fire barriers. The machine guns must be ready at all times to stop by instantaneous fire all hostile attack. In order to have machine gun protection at all, it is absolutely necessary that they be protected from bombardment. This is best done by the following: Place the machine guns under solid cover; make their emplacement invisible; echelon the machine guns in depth. The cover must be placed where it can be hidden from the sight of the enemy, such as a counter slope, a position where it is impossible to blend it, relief with an accentuated slope of the ground, woods, brush, etc. It is essential that the principal parts of the machine gun casemate be prepared in the rear. Only in this manner will the work be done solidly and rapidly. While the machine gunners and helpers do the excavating, specialists in rear prepare the parts for assembling. The latter are then transported to the position and, the casemate is established, hiding the work with the greatest care from enemy observation. Remember that it is of the utmost importance that the machine gun be invisible, so the firing emplacements must be made outside of the shelter, but near enough for the gun to be brought out instantly and put into action. All communicating trenches leading to the firing emplacement must be concealed. Enough emplacements should be built to avoid firing daily from the emplacements especially reserved for cases of attack. Do not place too many machine guns in the first line; in case of a violent bombardment they are sure to be destroyed. The object to be attained is to install the machine guns in conditions such that if the enemy penetrates our first line, by aid of his bombardment or asphyxiating gas, his infantry, as it advances, comes under the fire of machine guns echeloned previously in depth, under whose fire it must stop. It is not a matter of sweeping a wide sector, but of giving over certain strips of ground flanking fire which will cut down surely the enemy's waves when they push forward. The commander should, therefore, divide between the first line and the terrain in rear, the machine guns which he controls, organizing for each particular case a firing emplacement in accord with the surrounding ground and the purpose in view.

General Rules For Installation.

Machine gunners must under no circumstances abandon their positions. They must, when necessary, allow themselves to be surrounded and defend themselves in their place to the end. In many cases the heroism and tenacity of a few machine gunners have permitted the rapid retaking of a lost position. To provide for this resistance to a finish, the machine gun emplacements must fulfil the following conditions:

1. Be surrounded by a wire entanglement of irregular trace and as invisible as possible.

2. In the enclosure thus created having several firing emplacements, in case one or more becomes useless.

3. The personnel must have all the means for protection against gas and have in addition rations, water and abundant ammunition.

Employment Of Fire And Instruction.

The more grazing the fire of a machine gun the more effective it is. This causes the principal employment of the machine gun to be at distances where the trajectory is flattest, that is under 800 or 1,000 yards. However, the effort to obtain a grazing fire must not exclude long distance fire. This latter will always be justified when directed upon important objectives, or necessary points of passage. For this fire to have some efficacy, it is necessary to calculate the range with the greatest precision. On the defensive indirect fire will be employed sometimes to annoy the supply, reliefs, etc. To give results, great quantities of ammunition will have to be expended. All of the officers and non-commissioned officers and as many men as possible must be capable of firing the machine gun, so that at the time of an attack no gun will remain idle for want of personnel. It is, moreover, essential to keep up the training of the personnel by having them fire at least twice a month, and, if possible, once a week.