79.—Have several emplacements.
Several emplacements should be provided so that mortars, etc., may be removed as soon as they have obtained desired results or been located by the enemy.
The trench mortar commander should make it his business to study carefully all possibilities for effective emplacements and should inspire his men to be alert and quick to improve opportunities.
80.—Use of machine guns.
The machine guns should likewise be handled as a mobile weapon and not be used merely from elaborate carefully concealed emplacements commanding otherwise uncovered ground or enfilading communication trenches, etc.[C]
81.—Use of hand grenades.
Hand grenades may be listed as trench artillery. The temptation is to use them too freely. Like other ammunition they should never be wasted and always used with a definite aim.
FOOTNOTE:
[C] Captain Hanguillart treats this important subject very summarily. Cf. Cole & Schoonmaker's Military Instructor's Manual p. 319. He also barely mentions Gas attacks. Cf. very complete treatment in same work, p. 356 to 370.