_Craters._--The question of the occupation of craters must be decided by an authority higher than the platoon commander. In certain cases it is well to occupy them; in others, inadvisable. We will discuss only the practical work to be done in each case. _Craters to be occupied._--Crown the rim on the enemy side with a continuous trench, joined to the lines by (at least) two communicating trenches. Run out galleries in three directions, first for protection and later for use in the attack. Construct bombproofs on the half cone on the enemy side. A crater is a position advantageous for the construction of auxiliary defenses, for the removal of earth from the galleries, for massing troops for an attack, and for flanking the lines. _Craters that the enemy occupies._--They should be hampered with bombs and grenades. We should head off the enemy by means of two well-placed mine chambers, which are always possible to fire rapidly when the scheme of defense is by independent galleries. _Craters not occupied._--It is well to see what goes on at the bottom. An outpost of several men or a sentinel may be posted for this purpose in a communicating trench on the friendly rim. Two communicating trenches may also be used to crown the friendly rim with a trench with slight counterslope. The outposts place a dozen loopholes permitting fire on the bottom. We may also fill up the bottom with chevaux de frise and other auxiliary obstacles that can be thrown in. If the craters are in the way, we can always turn them by mining. (See figures for different examples:) [Illustration: Fig. I. --Example of Mine Craters-- 1 Mine Crater to be occupied t First line trench E Crater B B^1 B^2 Communicating trench T Trench crowning rim on enemy side M M^1 Machine gun on flanks E E^1 E^2 New galleries R Wire entanglement] [Illustration: Fig. II. --Mine Crater occupied by the enemy-- E Mine Crater T 1^{st} line trench G^1 Gallery destroyed by explosion G G^2 Intact galleries allowing explosions to be placed F F^2 Which fill up enemy crater] [Illustration: Fig. III. --Mine crater not to be occupied-- t Jumping off trench T Trench crowning friendly rim 1 2 3 4 5 Loopholes overlooking the bottom and enemy rim M M^1 Flanking automatic rifle R Wire entanglement] [Illustration: Fig. IV. Mine Crater between two lines Aim:-- Create an elevated earth position for placing machine guns or throwing bombs at M and M^1 which enfilade the portion t & t^1 of enemy trench.] [Illustration: Fig. V. Mine Crater for flanking purposes, see Fig. I & III. Fig. VI. Destroying a portion of enemy trench by means of two mine craters. B B^1 Communicating German trenches cut off by explosion. S S^1 Salient under which E.E are exploded. All flanking machine guns between S & S^1 cut off by rims of craters.] TRANSCRIBER'S NOTE