EN0065 Lesson 2 Practice Exercise Answer Key

LESSON 2

SELF TEST

ANSWER KEY AND FEEDBACK

1. What are the two purposes for the construction of trenches?

Trenches are excavated as fighting positions and to connect individual foxholes, weapons emplacements, and shelters in the progressive development of a defensive area.

2. Would you say that trenches are easy or difficult to camouflage?

Trenches are difficult to camouflage and are easily detected, especially from the air.

3. What is the purpose of the crawl trench?

The crawl trench is used to conceal movement into or within a position and to provide a minimum of protection.

4. What depth and width should a crawl trench be?

Crawl trenches should be 24 to 30 inches in depth and about 24 inches wide.

5. How far is the berm line located in front of the fighting trench?

The berm line is located about 18 inches from the front edge of the trench.

6. To what initial depth is the fighting trench dug?

The trench is dug to a depth of 3 feet below ground level. At this point, a man can fire in a kneeling or crouching position.

7. How is the front parapet of a fighting trench constructed in order to help prevent its detection?

The crest of the parapet should be irregular to aid concealment.

8. If spoil is available, why should the rear parapet of a fighting trench be higher than the front parapet?

If spoil is available, the rear parapet should be higher than the front parapet to prevent silhouetting of soldier's heads when firing.

9. When can parapets of fighting trenches be omitted?

Parapets can be omitted to aid concealment or when ground provides background and protection to firer's rear.

10. How is the floor of the fighting trench prevented from becoming wet and muddy?

A sump is dug at the lowest point to prevent the floor of the trench from becoming wet and muddy.

11. The necessity for revetment of walls may sometimes be avoided by what procedure?

The necessity of revetment of walls may sometimes be postponed or avoided by sloping the walls of the excavation.

12. In most soils, what slope is sufficient to avoid revetment?

In most soils a slope of 1:3 or 1:4 is sufficient.

13. What is a serious disadvantage of having sloping walls of trenches?

Wall sloping can seriously reduce the protection provided due to the increased width of the trench at ground level.

14. What is the purpose of facing type revetment of trenches?

Facing type revetment serves mainly to protect revetted surfaces from the effects of weather and damage caused by occupation.

15. What condition or type of soil permits the use of facing revetment?

Facing type revetment can be used when soils are stable enough to sustain their own weight.

16. What methods of support are used to keep the revetment in place?

Methods of supporting the facing revetment are timber frames and pickets.

17. Sandbags can be used for revetting and the repair of trenches. How full must the sandbags be?

Sandbags are uniformly filled about 3/4 full.

18. How should sandbags be placed with reference to side seams or stretchers and choked ends on headers?

Sandbags are placed so side seams on stretchers and choked ends on headers are turned toward the revetted face.

19. What two pieces of equipment can be used to expedite the filling of sandbags?

Two pieces of equipment that can expedite the filling of sandbags are the intrenching machine and the funnel.

20. Dummy trenches are dug to conceal from the air or ground, the true extent of the defended area. How deep should they be dug and what means taken to make them effective?

Dummy trenches should be dug 18 inches deep with brushwood laid in the bottom.

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Lesson 3
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