CROSSING A BOMBARDED ZONE.
121.—Case I. Artillery opening fire to register.
A registering fire is easily recognized as the German artillery registers either with a single percussion shell at a time, or with two time-shells at three seconds interval.
In the German field gun, the setting of the angle of sight[E] and of the elevation[F] involves two operations.
122.—Oblique to right then to left.
Therefore infantry under registering fire should oblique forward rapidly.
123.—Case II: Artillery opening fire for effect.
The zone has necessarily been previously registered. Such a zone is easily recognized by the presence of shell holes.
124.—Avoid Zone if possible.
It should be avoided and the advance made on its outskirts.
125.—The five cases of fire for effect.
If this cannot be done and the fire for effect materializes five cases are to be distinguished as the shells may be:
1. Shrapnel shells bursting at right height;
2. Shrapnel shells bursting high;
3. Time-Fuse high explosive shells bursting at right height;
4. Time-Fuse high explosive shells bursting high;
5. Percussion high explosive shells.
126.—Case 1. Burst Area of Shrapnel shells bursting at right height.
The area of burst is about 250 to 300 yards in length and 30 yards in width, half the bullets falling on the first 50 yards of the beaten zone.
127.—Protective Formation against Shrapnel.
Advance in line of section, in single or double file keeping as closed up as possible with 30 yards intervals between sections.
The second line should be 250 to 300 yards behind the first.
128.—Case 2. Shrapnel shells bursting high.
Much less dangerous than when bursting at right height as initial speed of bullets is spent. Same formation as for Case 1.
129.—Case 3. Burst area of Time-fuse high explosive shells bursting at right height.
The area of burst is opposite to that of shrapnel: short depth, large width, only 7 to 10 yards depths as opposed to 60 to 100 yards in width.
130.—Protective Formation against Time-fuse high explosives.
Advance in line of section, single or double file, keeping as closed up as possible with 60 to 100 yards intervals between sections.
The second line may be 15 yards behind the first.
131.—Case 4. High explosive shells bursting high.
The depth of the area of burst is longer than when shells burst at the right height; therefore widen interval between the lines.
132.—Case 5. Burst area of percussion high explosive shells.
The radius of the explosion is only about 25 yards but the local effect is intense and the displacement is effective in more than double the radius.
133.—Protective Formation against percussion high explosive shells.
Advance in line of section in double file, keeping as closed up as possible, with about 100 yards intervals between sections.
The second line may be about 50 yards behind the first.