ed;
fords and roads obstructed; tracks torn up; telegraph lines cut, and
houses, villages, woods and fields fired. Demolitions and obstructions
are prepared by engineers, assisted, if necessary, by other troops
detailed from the reserve, and are completed by the mounted engineers
of the rear party at the last moment.

The instructions of the supreme commander govern in the demolition of
important structures.

OUTPOSTS

(See "Outpost," Par. 887)

=1051. Definition and Duties.= Outposts are detachments thrown out to
the front and flanks of a force that is in camp or bivouac, to protect
the main body from being surprised and to insure its undisturbed rest.
In fact, an outpost is merely a stationary advance guard. Its duties,
in general, are to _observe_ and _resist_--to observe the enemy, and
to resist him in case of attack. Specifically its duties are:

(=a=) To observe toward the front and flanks by means of stationary
sentinels and patrols, in order to locate the enemy's whereabouts and
learn promptly of his movements, thus making it impossible for him to
surprise us.

(=b=) To prevent the main body from being observed or disturbed.

(=c=) In case of attack, to check the enemy long enough to enable the
main body to prepare for action and make the necessary dispositions.

=1052. Size.= The size of the outpost will depend upon many
circumstances, such as the size of the whole command, the nearness of
the enemy, the nature of the ground, etc. A suitable strength for an
outpost may vary from a very small fraction to one-third of the whole
force. However, in practice it seldom exceeds one-sixth of the whole
force--as a rule, if it be greater, the efficiency of the troops will
be impaired. For a single company in bivouac a few sentinels and
patrols will suffice; for a large command, a more elaborate outpost
system must be provided. The most economical form of outpost is
furnished by keeping close contact with the enemy by means of outpost
patrols, in conjunction with resisting detachments on the avenues of
approach.

Troops at a halt are supposed to be resting, night or day, and the
fewer on outpost the more troops will there be resting, and thus
husbanding their strength for approaching marches and encounters with
the enemy. Outpost duty is about the most exhausting and fatiguing
work a soldier performs. It is, therefore, evident that not a man or
horse more than is absolutely necessary should be employed, and