The advance guard is a detachment of the main body which precedes and covers it on the march. The primary duty of an advance guard is to insure the safe and uninterrupted march of the main body. Specifically its duties are: 1. To guard against surprise and furnish information by reconnoitering. 2. To push back small parties of the enemy and prevent their observing, firing upon, or delaying the main body. 3. To check the enemy's advance in force long enough to permit the main body to prepare for action. 4. When the enemy is encountered on the defensive, to seize a good position and locate his lines, care being taken not to bring on a general engagement unless the advance guard commander is empowered to do so. 5. To remove obstacles, repair the road, and favor in every way the steady, march of the column. The strength of the advance guard will vary with the proximity of the enemy and character of the country; for a regiment it will generally consist of from two troops to a squadron, for a squadron of one troop; for a troop of from a section to a platoon. The advance guard commander is responsible for the proper performance of the duties with which it is charged and for its conduct and formation. The advance guard provides for its security and gains information by throwing out to the front and flanks smaller bodies: Each part must keep in touch with the unit from which it is sent out. An advance guard is generally divided into a reserve and a support; where it consists of less than a squadron, the reserve is generally omitted. The support sends forward an advance party, which, in turn, sends forward a point. In small advance guards the point precedes the advance party about 350 yards, the advance party the support about 500 yards, and the support the main body about 600 yards. Where advance guards are large enough to require a reserve these distances are increased about one-fourth, the reserve following the support, the main body following the reserve at a distance varying from 500 to 800 yards.