8.  The duties of the relieved commander are: 
(1) To turn over his sector thoroughly policed and in good
condition as regards its construction and the new work,
if any, in progress.
(2) To turn over his supplies in good condition and fully
accounted for.
(3) After reporting the relief, to march his men back to
billets as promptly and secretly as possible, in column
of files, platoon leaders in the rear of their platoons,
a non-commissioned officer and guide at the head of each.
(4) On the evening preceding relief, to send his cooks back
to billets so that his men may be provided with a hot
meal immediately on arrival.

D. If an attack occurs during the march through the boyaux, to or
from relief, the company affected occupies the nearest
defensive position and at once notifies its battalion
commander.  If an attack occurs during the actual process of
relief, the senior officer present takes command.

II.  The Stay in the Trenches.

   A. THE FOUR OBJECTS OF A TRENCH COMMANDER: 

1.  Security of his sector. 2.  Protection of his troops. 3.  Constant and accurate observation. 4.  A continuous offensive.

B. HIS PLAN OF DEFENSE: 

1.  General principles of defense:  (a) Arrangement in depth.  The most dependable defense is in prearranged counter attacks.  The system of defense must react like a helical spring. (b) Tenacity of defense. 1.  Each unit must be prepared to hold its post to the last extremity. 2.  Orders to withdraw will never be obeyed unless unmistakably valid. 3.  All ground lost must be retaken at once in counter attack by the unit which lost it. (c) Apportionment of responsibility.  Each active segment must have a commander responsible for its defense, upkeep and sanitation, and the discipline and instruction of his men.

2.  Basis: 
(a) The plan of defense turned over by the preceding commander. 
This will usually suffice for the first 24 hours after
relief.
(b) General information of the enemy’s lines, dispositions, and
intentions, based chiefly on aerial photographs.

   C. ORGANIZATION OF DEFENSE: 

   1.  Allocation of front. (The front of an American battalion will
      average about 1,000 yards.)
      Diagrams:  A. The Regiment.  B. The Battalion.  C. The Company.  D.
      The Platoon.
   2.  Distribution of effectives.  Determined chiefly by the terrain
      and by 3.
   3.  Employment of the several arms: 
      (a) Machine guns.  Crew of 8 men per gun. (Furnished by
          detachments of a machine gun company.) Located by the
          infantry commander, in concealed emplacements behind the
          first line, to deliver successive barrages from flanking
          positions.  Effective range:  up to 700 yards.
      (b) Automatic