11. Keep up reconnaissance.
12. Use the reserve, but not until needed or a very favorable opportunity for its use presents itself. Keep some reserve as long as practicable.
13. Do not hesitate to sacrifice the command if the result is worth the cost.
14. Spare the command all unnecessary hardship and exertion. (536)
MACHINE GUNS
[551]. Machine guns are weapons of emergency. Machine guns must be considered as weapons of emergency. Their effectiveness combined with their mobility renders them of great value at critical, though infrequent, periods of an engagement. (537)
[552]. Machine guns to be used for short periods, when opportunities present themselves. When operating against infantry only, they can be used to a great extent throughout the combat as circumstances may indicate, but they are quickly rendered powerless by efficient field artillery and will promptly draw artillery fire whenever they open. Hence their use in engagements between large commands must be for short periods and at times when their great effectiveness will be most valuable. (538)
[553]. Machine guns attached to advance guard; use in meeting engagements. Machine guns should be attached to the advance guard. In meeting engagements they will be of great value in assisting their own advance, or in checking the advance of the enemy, and will have considerable time to operate before hostile artillery fire can silence them.
Care must be taken not to leave them too long in action. (539)
[554]. Use of machine guns with rear guard. They are valuable to a rear guard which seeks to check a vigorous pursuit or to gain time. (540)