[613.] The strength and composition of hostile troops must be observed. If they can not be counted, their strength may be estimated by the length of time a column consumes in passing a given point, or by the area covered if in camp.
Patrol leaders should know, if practicable, the uniforms, guidons, etc., of the enemy, as it will assist in determining the class of troops seen when no other means for doing so are available.
Insignia from the enemy's uniforms, picked up by patrols, often convey valuable information by indicating what troops are in the vicinity.
[614.] Patrols avoid fighting, except in self-defense or in order to prevent the enemy's patrols from gaining valuable information, or when necessary in order to accomplish their mission. In such cases, a patrol should fight resolutely even though inferior in numbers.
[615.] Information gained by patrols is generally of no value unless received in time to be of use to the commander. Patrol leaders must therefore send back information of importance as soon as it is gained unless the patrol itself is to return at once.
[616.] If written, messages should state the place, date, hour, and minute of their dispatch. The information contained in them should be clearly and concisely expressed. They should be signed by the patrol leader.
The authorized message book should be used and the form therein adhered to.
[617.] If the message be an oral one, the patrol leader should require the messenger to repeat it before starting back. In general, an oral message should cover but one point. Except when there is little chance of error in transmission, messages should be written.
[618.] When in friendly territory and not very far from friendly troops, one messenger is sufficient unless the message is very important. In hostile territory, either two men should go together or the message should be sent in duplicate by different routes.
[619.] Whether the information gained is of sufficient importance to be reported at once or may await the return of the patrol is a question which must be decided in each case. In case of reasonable doubt, it is generally better to send the report promptly. If the patrol leader has received proper instructions before starting out and has the requisite ability to lead a patrol, he can generally decide such questions satisfactorily as they arise.