PREVENTION OF FROST BITES AND TRENCH FEET 142 TRENCH WARFARE LOCATION AND CONSTRUCTION OF TRENCHES In locating the site for a defensive firing line, it must be divided into three sections:--firing line, immediate support and reserves. In doing this several opposing factors should be taken into consideration and their relative importance judged according to the special circumstances and objects in view, keeping in mind the probable lines and manner of defense of the enemy, and whether the trenches are for permanent or for temporary use. This may be summarized under two heads: first, with the object of attaining the greatest field that can be covered by defensive fire; and, second, the greatest security from offensive fire. It will even be found that these two constructions will be in conflict. Trenches placed behind the crest of a hill, say fifty to one hundred and fifty yards from the top, will hamper the accuracy of the enemy’s artillery fire. Shooting, to be effective, calls for a high rate of accuracy, and here the only observations possible are from aircraft and balloons; but the enemy side of the hill will be raised ground to the occupants of the trench. At night large numbers of the enemy could collect there, and the dangerous space to them would merely be the distance from your fire trench to the crest of the hill. The enemy could and would entrench themselves on their side of the crest and by raising their parapet enjoy the advantage of a higher front, which would eventually lead to their entirely controlling the area behind your trenches, which are continually used by the relief and fatigue parties. It is a principle that grazing rifle fire upon a defensive enemy is more effective than plunging fire, but any entrenched position higher than your own held by an enemy gives them a tremendous advantage. Regardless of what opinion may be held as to the maximum depth of a field of fire required to meet or repel attacks, whether in masse or open order, it should be obvious that the greater the depth of the field of fire and the more extensive the view of the enemy’s operations, the better it will be for the defending forces. Protection from and localization of artillery fire must be provided by the internal construction of the trench rather than by a position that protects but also restricts the field of fire. There are frequently found in front of a firing line small areas of ground which are not covered by direct fire from your trench. A flanking fire frequently can cover these areas, but in spite of this, they must be watched constantly by means of listening posts or concealed observation posts, which may be hidden by the banks of rivers, hedges, ruined houses, or whatever natural existing concealment renders observation possible.