In all formings from file, the leaders of ranks instantly cover each other, take the ordered front and halt. See American Military Library.
In the covering of files on horseback, the same directions hold good as on foot. In addition, it must be scrupulously observed that every man’s horse stands exactly straight to the same front as that of the man before him. Both in the horse and foot drill, the men should be often practised in covering. The former are thereby taught to place their horses straight under them.
Close Files of infantry, are soldiers standing in rank, contiguous to one another, upon any given depth of line or column. Whenever a regiment marches in front, every man should feel the arm of his next man which ever way he dresses; but he must not lean on him, nor must he move his arm from the body to feel him. So that close files mean nothing more than that soldiers in the ranks should lightly touch each other, without crowding or pressing.
Open Files, are soldiers standing in rank at given distances without touching one another. The formation at open files is only practised as a preparatory drill for forming at close files, (which is the order for action) so that every man may be taught to stand and move in a proper position, without acquiring a habit of leaning upon his neighbor. On this account every intelligent officer who has the management of recruits, will form them sometimes at open files, and march them in that order. Soldiers that have been regularly drilled, should likewise be occasionally practised in advancing by open tiles.
Double Files are formed by the left files in each rank stepping to the rear of the right files; or the contrary.
Indian Files, a line of men advancing or retreating from either of the flanks, from the centre or from any proportion of a line in succession to one another. They are sometimes called goose files; but the term is only familiarly, or rather vulgarly used among soldiers, and derives its appellation from a flock of geese, generally following a leader, one by one. The Prince de Ligne, says, that men march forward in file, or en ordré mince, par une instinct moutonnier, meaning, that they follow each other like so many sheep, who move by instinct.
File-leader, is the soldier placed in the front of any file, or the man who is to cover all those that stand directly in the rear of him, and by whom they are to be guided in all their movements.
File leaders must be particularly careful to preserve their proper distances from which ever hand they are to dress, and the followers of each file must only be attentive to cover, and be regulated by their proper file leaders. In file the rear rank invariably dresses by, and is regulated by the front rank.
To double the Files, is to put 2 files into one, making the depth of the battalion double to what it was, in number of men. Thus four deep are double files.
File marching on foot, all recruits must be taught first to face, and then to cover each other exactly in file, so that the head of the man immediately in front may conceal the heads of all the others behind him. The principal points to be attended to are, that the men move in equal time an equal pace of 2 feet, that the front rank men cover exactly, and that the rear rank men keep closed and dressed to the front rank.