4. From the largest caliber guns: 15 to 25 feet of earth.
The following table shows the penetration of the German S bullet at a range of 200 yards:
| Inches | |
| Steel plate | ⅜ |
| Broken stone | 6 |
| Brickwork, cement and mortar | 9 |
| Brickwork, lime and mortar | 14 |
| Sandbags | 24 |
| Sand, loose | 30 |
| Hardwood, oak, etc. | 38 |
| Earth | 50 |
| Soft wood, poplar, etc. | 58 |
| Clay | 60 |
| Dry turf | 80 |
In addition to the regular "dugouts" for the supports, the latest type trenches have squad dugouts just in rear of the bays of the fire trench. These provide shelter during bombardment for the members of the squad not actually required on duty in the trench bay.
Plate 24a.—Section of traversed type of fire trench showing entrance to squad dugout.
Communications
The fire trench is connected with the cover for supports by a system of zigzag trenches having the profile shown in Plate 23. The arrangement is shown in Plate 1.