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.
   (c) 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.