hence they are covered. The cover (roof) must be thick enough to afford
protection from high angle artillery fire. It is placed as near the fire
trench as possible.

(4) Approach Trenches. These connect fire trenches with the support
trenches and the support trenches with any trenches in rear where
natural covered communication is impracticable.

[Illustration: CROSS SECTION OF A SUPPORT TRENCH AND DUGOUT]

[Illustration: A SECTION OF A FORWARD ENTRENCHED ZONE

OTHERS ARE IN REAR]

They are zig-zagged to escape being enfiladed. (That is, to prevent one
explosion from doing too much damage in a single trench.) During an
engagement, troops by using these trenches can go safely to the help
of the troops in the fire trenches. They are usually deep and narrow.

(5) Intermediate Trenches. They are constructed in rear of the support
trenches when the ground renders it possible to offer a stubborn
resistance between the support and the reserve trenches. They are
constructed like fire trenches.

(6) Reserve Trenches. Constructed like the fire trenches and occupied
by the local reserves who live in deep dug-outs. The intermediate and
reserve trenches are often merged into the support trenches. All are
protected by barbwire entanglements. No set plan of trenches can be
used. The topographical features of the ground must govern.

MILITARY MAPS

Definition. "A military map is a drawing made to represent some
section of the country, showing the features that are of military
importance, such as roads, bridges, streams, houses, and hills. The map
must be so drawn that you can tell the distance between any two points,
the heights of the hills, and the relative positions of everything
shown." (Field Service Regulations.)

In the field the military maps are supplemented by sketches, or field
maps, prepared from day to day. For facility in reading, military maps
are made according to a uniform system of scales and contour intervals
as follows:

Road Sketches. Three inches on the map is equal to 1 mile on the
ground, contour intervals of 20 feet.

Position and Outpost Sketches. Six inches on the map arc equal to 1
mile on the ground, contour intervals of 10 feet.

Manoeuver or War Game Maps. Twelve inches on the map are equal to 1
mile on the ground, contour intervals of 5 feet.

Large Strategical maps for Extended Manoeuvers. One inch on the map is
equal to 1 mile on the ground, contour intervals of 60 feet.

Ever