=100.= =The Garrison.=--The garrison should consist of artillery and infantry, and, in an intrenched camp, of enough mounted troops for escort, messenger, and a limited vedette service. The strength of the infantry is generally regulated so as to give a suitable garrison to each detached work, and about 1½ to 2 men for each yard of the front of attack. The artillery is allowed about 12 men for each gun. The number of engineers is determined for each place by the probable amount of engineer work that will be required. These troops make up about one-third of the entire force. A general reserve of all arms (principally, however, foot troops) makes up the other two-thirds, and is held as “a fighting force” for preventing the investment of the place, or for breaking up the investing lines when established. This reserve is called upon for work on the front of attack or in the trenches only when it cannot be avoided. In smaller places the portion of the garrison called upon for the outer line of defence may be increased to one-half or two-thirds, and the general reserve be reduced to one-half or one-third of the entire force. When the investment is strongly established the general reserve will usually be combined with the other troops. The troops engaged on the front of attack are usually assigned to the different sectors of attack and are divided into reliefs (ordinarily three), each relief having as a rule a tour of one day in the front lines, one in the immediate supports, and one in the reserve and in interior fatigue duty. The Governor, however, so regulates the details as to impose upon the troops the least work consistent with an energetic defence. =101.= =Armament.=--The guns for arming the place should be placed in position or in store within the works before the beginning of hostilities. There should be mounted in commanding positions a sufficient number of high-power guns to hold the enemy’s first works at a distance and to fire upon his camps, etc., if placed too near. In addition to these, a full supply of light guns, including machine and rapid-fire guns, should be at all times equipped and supplied for immediate use in meeting an assault or surprise. Their emplacements, platforms, etc., should be in readiness for use at any moment. In large places and for an active defence there will be needed also enough field-guns to properly equip the general reserve (about 4 guns per 1000 men). These should be considered a part of the equipment of the reserve.