The figures on pages 181 and 182 show to what extent the ground is capable of increasing or diminishing the efficacy of fire. The French assert that the Würtembergers deliberately applied these principles in the defense of the park wall at Villiers. It was, at any rate, only an accident that the masses of troops on the west side of the gently sloping Mamelon de Villiers suffered heavy losses on November 30th, 1870.
General Paquié of the French Army[1] lays down the following rule: "When the angle of slope of falling ground corresponds to the angle of fall of the lowest trajectory of a cone of dispersion, the depth of the beaten zone will be 2-1/4 times greater than on level ground. When the angle of slope of falling ground is equal to the angle of fall of the mean trajectory of a cone of dispersion, the depth of the beaten zone will be 2-1/2 times greater than on level ground. When the lowest trajectory of a cone of dispersion passes over the crest of a hill at the height of a man, and when the reverse slope of that hill is equal to 1/100 of the range, the depth of the beaten zone will be five times as great as on level ground."
These data are of no practical value in war. They serve only to increase the appreciation of fire effect when examining the terrain, and train the eye in judging such situations.
The character of the ground may exert great influence when firing on intrenchments. Fire delivered from low ground against an enemy in shelter-trenches is absolutely ineffective—as shown in the action against the French IInd Corps at Point du Jour and by the experiences of the Russians at Plevna and Gorni Dubniac. This condition becomes aggravated the smaller the angles of fall of the projectiles, and the higher the target is situated relative to the firing position of the attacking party.
Attacks on hill positions show that there is a range at which the greatest efficacy may be obtained from fire directed against the top of the height itself. This maximum efficacy gradually dwindles as the position is approached. This fact has led the Swiss to retain a Main Firing Position. (See Figure, p. 182. Fire effect from A and from B). For the purpose of determining the favorable range, "D," corresponding to a certain height (of the enemy's position) "H," Lieutenant-General Rohne has deduced the following formula for rifle model '88:[2]
D = 15 . H + 500.
- ↑ See also Le tir de guerre et les expériences pratiques du camp de Châlons. Journal des sciences militaires, Sept., Oct., Nov., 1808—Le Joindre Général. Petit Guide pour les tirs collectifs, 1904.
- ↑ Capitaine Cugnac, D = 14 (H + 50). See also the work of Captain Knobloch, Zur Technik des Feuerangriffs gegen Höhenstellungen, Swiss Monthly Journal, 1907. The well-known plateau of the "Galgenhügel" at Wörth, which is at present crowned by the monument of the 50th Infantry (elevation 35 m.) could be effectively swept by the fire of our present-day weapons at 1025 m.; a further advance would reduce the fire effect. For rifle model '98 the formula might be stated: 20 . H + 600.
