=4. Rising Ground.=--(i) The more steeply the ground rises with reference to the line of sight, the greater will be the decrease in the extent of the beaten zone. For example, when firing with Mark VI ammunition at ground rising 2, 5, and 10 degrees, the depth of the beaten zone at 1,500 yards range is decreased roughly by quarter, half, and two-thirds respectively (Fig. 8). Since the grouping of the bullets becomes closer as the upward slope of the ground increases, the effect of errors in estimation of range will be more serious, and as the bullets will fall at a steep angle the dangerous space will be proportionately reduced. [Illustration: _The Beaten zone is greatest on slope A-D, the Trajectory being practically parallel to the surface of the ground._ =Fig. 8.= THE RELATION OF GROUND TO FIRE EFFECT.] [Illustration: =Fig. 9.= THE RELATION OF GROUND TO FIRE EFFECT.] (ii) =Formations, Supports, and Reserves.=--As a general rule, therefore, on ground which rises with reference to the line of sight, _troops should be drawn up in shallow formations, but supports and reserves may be nearer the firing-line than is normally advisable_. =5. Falling Ground.=--(i) When the ground beaten by bullets falls in respect of the line of sight, _the depth of the beaten zone is augmented in proportion as the downward slope increases, until it reaches its greatest magnitude when the angle of the fall of the bullets is the same as the slope of the ground_; or, in other words, when the trajectory is practically parallel to the ground surface (Fig. 8, Depth of Zone, A--D). In these circumstances the fire becomes _grazing_ (Fig. 9), _and the extent of the dangerous space is nearly identical with the beaten zone_. (ii) _At close ranges_, therefore, where the trajectories are flat, the depth of the beaten zone will be much increased if the ground behind the target _falls at a gentle slope_ (Fig. 9, A). _At long ranges_, on the other hand, a greater area will be beaten when ground falls more steeply (Fig. 9, C). (iii) For example, at 1,500 yards range the depth of the beaten zone is roughly increased by three-fifths when the bullets strike ground falling at 2 degrees. On ground falling at 5 degrees, which is nearly parallel to the trajectory at this range, the depth beaten is about ten times greater than on level ground. (iv) It is clear, therefore, that falling ground _far behind the objective will at times be swept by unaimed fire_, and it follows that in such circumstances supports should either be under cover or, if there is no cover, in shallow columns on narrow frontages with the object of reducing target surface as much as possible.