Page:Tactics (Balck 1915).djvu/210



the above example because the efficacy of infantry fire in battle will approximate theirs more nearly than any other. From this we may deduce that where the ground slopes upward in rear of a firing line, less distance will suffice to withdraw supports from the fire directed at the firing line than on level ground; and that, if the ground in rear of the firing line slopes downward, the distances must be increased unless the slope is so great or the hostile trajectories so flat that bullets pass over the crest, forming a 'defiladed space,' into which no projectiles strike."
 * tance to the tactician. For this reason I have selected 'poor' shots for

On ground rising in respect to the line of sight (i. e., on the slope of heights facing the enemy, or opposite to commanding ground, the slope facing the plain) columns suffer the greatest losses; on ground falling in respect to the line of sight (on the reverse slope of hills and on plateaus) line targets suffer the greatest losses.

Where the ground falls at a greater angle than the angle of fall of the projectiles (about 5 degrees at 1500 m., and 1 degree at 800 m.) a defiladed space is formed, which makes it possible to bring supports nearer to the firing line than would be practicable on level ground. If we assume that each graduation of the rear sight over 600 m. commands a space 100 m. deep with the normal core of hits, we obtain the following depths of the beaten zones at a range of 1500 m., with rifle model '98 (angle of fall 5 degrees and 22 minutes):

Ground rising  1 in 10 = 6° =  50 m.   "     "      1 in 20 = 3° =  64 m.   "     "      1 in 50 = 1° =  81 m. Ground falling  1 in 10 = 6° = 360 m.   "     "      1 in 20 = 3° = 180 m.   "     "      1 in 50 = 1° = 113 m.