=651.= The advance of a troop after dismounting, in anticipation of fire action either in attack or defense is made in close order, preferably in columns of fours or twos, until the probability or the actual encountering of hostile fire makes it advisable to deploy. After such deployment the advance (now designated =the approach=) may be continued in line of skirmishers or other suitable formation before opening fire. The approach dismounted may often be facilitated, better advantage taken of cover, and losses minimized by using formations such as line of platoons each in column of twos or troopers, or a succession of thin lines at varying distances, one directly behind the other or echeloned. The choice of a formation would depend upon conditions, such as the effectiveness of the enemy's fire, cover afforded by folds of the ground, or by natural obstacles. If the deployment is found to be premature, it will generally be better to assemble the troop and resume the advance in close order. The formations mentioned as facilitating the advance, viz, line of platoons in column of twos or troopers, or a succession of thin lines find application most frequently in the approach when the ground is so difficult or the cover so limited as to make it desirable to take advantage of the few favorable routes on which to move forward. =652.= The approach in a succession of thin lines is, if possible, made by sections under the immediate direction of platoon commanders with wide intervals between skirmishers. By so advancing continuous control of the line is assured. If that method is not practicable, then the successive lines are made up of one or more men from each four of a platoon on the skirmish line, the command being: 1. =Numbers 1 (or such number or numbers), first (or such) platoon, forward=; 2. =MARCH.= The captain having pointed out in advance the selected position in front of the lines which are to be occupied, the designated numbers move to the front. The line thus formed preserves the original intervals as nearly as practicable; when this line has advanced to the indicated position, a second line is sent forward by similar commands, and so on at irregular distances until the whole line has advanced. Upon arriving at the indicated position the first line is halted. Successive lines upon arriving halt on line with the first, and the men take their proper places in the skirmish line. Ordinarily each line is made up of one man or more from each four of a platoon, and the men of a four are sent forward in order from right to left. The first line is led by the platoon leader of that platoon, the second by its file closer, and so on. Under favorable conditions the successive lines may be made up from all of the platoons which are deployed as skirmishers. The movement is conducted in quick time unless conditions make double time necessary. After the entire troop has reached the line a further advance in the same manner may be found advisable.