It must be explained to the men that odd numbers are right files, and even numbers left files. In order that the left four may always be complete, the file on the left of a squad will invariably move back, and the second file from the left always stand fast in forming fours. { 1. _When in line at the halt._--On the word { _Fours_, the left files will take a pace of 30 { inches back, and then a side pace of 30 inches _Form--Fours._ { so as to cover their right files, the first { pace being taken with the foot furthest from { the right files. In this formation the squad { will stand in fours. { On the word _Two-deep_ the left files will { move to their original position in line by _Form--Two-deep._ { taking a side pace of 30 inches, and a pace { forward of 30 inches; or if the squad has been { turned about while in fours, a side pace and a { pace back. [Illustration: PLATE II. FORMATION OF FOURS. _Fig. 1._ _Squad with an Odd File._ _Fig. 2._ _Squad with a Blank Odd File._ _Fig. 3._ _Squad with a Blank Even File._ _Fig. 4._ _When Squad is Turned about._] 2. _Forming Fours to the Right_ (or _Left_). _Form--Fours._ As already described. _Right_ (or } The squad will turn as ordered. _Left_). } _Left_ (or } The squad will turn as ordered, and then form _Right_)--_Turn_. } two-deep, as already described. If it is required to remain in fours, the word of command will be _In Fours_. _Left_ (or _Right_)--_Turn_. A squad moving to a flank in fours, on receiving the command _Right_ (or _Left_)--_Turn_, will turn in the required direction and form two-deep without any further word of command. On receiving an order to incline to the right or left, the squad will remain in fours. 3. _On the march._--A squad marching in line, or by the diagonal march, will be taught to form fours precisely as when forming from the halt; the right files marking time two paces whilst the left files are moving to their places. Should the word _Right_ or _Left_ or _Right_ or _Left Incline_ follow, the squad will turn in the direction ordered. 4. _When in file._--Fours will be formed by the left files, moving forward or back into their position in _Fours_, right files if on the move marking time two paces. 5. When moving in fours, the squad may be turned in any direction, diagonal or otherwise. 6. When moving in fours, the squad may be ordered to form two-deep; on the command, _Form--Two-deep_, the left files will step up or fall back into their places in two-deep formation, the right files marking time two paces.