=857.= Formal guard mounting will ordinarily be held only in posts or camps where a band is present. At the _assembly_ the men of each troop designated for guard form at stand to horse on their troop parade grounds, the noncommissioned officers falling in as file closers; the supernumeraries do not fall in; each first sergeant verifies his detail and inspects the dress and general appearance, replaces any man unfit to go on guard, turns the detail over to the senior noncommissioned officer, and retires. The senior noncommissioned officer then mounts, draws saber, and causes the detail to mount. The band, accompanied by the buglers, takes its place on the parade ground so that the left of its front rank shall be 12 yards to the right of the rank when the guard is formed. =858.= At _adjutant's call_ the adjutant takes post so as to be 12 yards in front of and facing the center of the guard when formed; the sergeant major takes post facing to the left 12 yards to the left of the front rank of the band; the band plays in appropriate time, the details are marched to the parade ground by their senior noncommissioned officers; the detail that arrives first is marched to the line so that upon halting the head of the horse of the man on the right shall be on line with and near to the sergeant major's horse, the noncommissioned officer, having halted his detail, places himself facing the sergeant major at a distance from him a little greater than the front of his detail, and commands: =DRESS.= The detail dresses on its right trooper; the noncommissioned officers of the detail in the line of file closers rein back so as to be 6 yards in rear of the rank; the noncommissioned officer in command of the detail then commands, =Front=, salutes, and reports, _The detail is correct_, or _(so many) sergeants, corporals, or privates are absent_; the sergeant major returns the salute; the noncommissioned officer in charge of the detail then passes by the right of the guard and takes post on the line of noncommissioned officers in rear of the right trooper of his detail. Should there be more than one detail, it is formed in like manner on the left of the one preceding; the privates, noncommissioned officers, and commander of each detail dress on those of the preceding details in the same rank or line. Should the detail from a troop not include a noncommissioned officer, one will be detailed to perform the duties of commander of the detail. In this case such noncommissioned officer, after reporting to the sergeant major, passes around the right flank between the guard and the band and retires. The troops detailed alternate in taking the right of the line.