formation of two deployed lines; 2d, a line of battalions
in columns of attack on the centre, or in squares by battalions; 3d, a
combination of these two, or the first line deployed, and the second in
columns of attack; and 4th, the deep formation of heavy columns of
several battalions. The tirailleurs are merely accessories to the main
forces, and are employed to fill up intervals, to protect the march of
the columns, to annoy the enemy, and to manoeuvre on the flanks.

1st. Formerly the line of battle for infantry was very generally that
of two deployed lines of troops, as shown in Fig. 26. But reason and
experience have demonstrated that infantry in this thin or light order,
can only move very slowly; that in attempting rapid movements it breaks
and exhibits great and dangerous undulations, and would be easily
pierced through by troops of a deeper order. Hence it is that the light
formation is only proper when the infantry is to make use of its fire,
and to remain almost stationary.

2d. If the formation of a line of battalions in columns of attack be
employed, the depth and mobility will depend upon the organization or
habitual formation of this arm.

In our service a battalion is supposed to be composed of ten companies,
each formed in three ranks. The two flank companies are designed for
tirailleurs. This would give a column of four divisions, and
consequently twelve files deep; and as only two of these files could
employ their fire, there would be much too large a portion of
non-combatants exposed to the enemy's artillery. In practice, however,
we employ the two-rank formation, which, if the flank companies be
detached, would give a column of attack eight files in depth, which is
not objectionable. If however, the flank companies should be present in
the battalion, the depth of the column would still be ten files.

In the French service, each battalion is composed of four divisions,
formed in either two or three ranks. The two-rank formation is the one
habitually employed. If all the companies be present, and the formation
in three ranks, the depth of column will be twelve files; if in two
ranks the depth will be eight, files. If the flank companies be
detached, the depth of column will be, for three ranks nine files, and
for two ranks six files. (Figs. 27 and 28.)

In the Russian service each, battalion has four divisions of three ranks
each. But the third rank is employed as tirailleurs, which gives a dept