complished by placing: 1st, some groups or line of groups
farthest from our main body and closest to the enemy in order to
observe, to report the movements of the enemy, and, when necessary, to
make a temporary resistance; 2d, a line of resistance ("supporting
groups") called "supports" upon which the first line can retire before,
being swamped by superior numbers; 3d, large groups, or line of groups
("line of reserves"), so located that they may go to the assistance of
the second line in case of necessity. Such arrangements may be
illustrated by the following diagram.

[Illustration:

PLATE SHOWING THE MAIN IDEAS INVOLVED IN SECURITY

Danger zone
Cavalry

Danger zone ---- Danger zone
--- ---
Cavalry -- __ -- Cavalry
-- -- -- --
/ -- -- \
/ / ___ \ \
+ / ---- ---- \ +
^ + / \ +
/ ^ + +-----------+ +
/ \ | MAIN BODY | ^
/ \ +-----------+ \
Line of observation. \ Line of reserves -
Occupied by small \ to move forward to
groups. Drive back \ help line of supports.
enemy patrols. \
Line of supports on line of resistance.
Rallying point for small groups in front.

Note that distances from the line of observation to the main body
increase as the groups increase in size. The reserves are the largest
groups. The groups on the Line of observation are the smallest.

It is most important to note that the groups are placed according to
the conditions and circumstances of the particular case. Don't follow
any blind rules. Your judgment must tell you when to place this group
here and not to place that group there. Have as few men on such duty as
practicable.

If a swamp, or a large body of water here, very small groups will
afford the necessary security.

If a forest, or steep hills here, very small parties will afford the
necessary security.

Assume that we want to afford security for o