Column is a military formation several ranks in depth, and of any length of front, adopted for convenience of movement; line formation being only two ranks deep and suited for actual fighting in consequence of the wide front of fire that can be developed. Previous to the introduction of the breechloading rifle, and the consequent increase in the advantages of a wide front of fire, most European nations fought in column, and especially the French, who, under the first Napoleon, sometimes formed very heavy columns of infantry by ranging many battalions in line, one behind the other. British infantry always fought in line. A thin single rank formation is now universal for the leading troops in battle; but the supports move in column until obliged, by hostile fire, to deploy into line.
A British battalion in column has its companies each two deep, one behind the other, at distances equal to the front of one company, so that on wheeling into line to either flank, no gaps are left. In half-column these distances are halved, and in quarter-column they are reduced to six paces.
Cavalry may be formed in columns of four squadrons, or eight troops; or each squadron may be formed into a column of two troops, the wheeling distance in each case being preserved or reduced as for infantry. Artillery form in columns of batteries, half-batteries, or divisions—i.e. with a front of six, three, or two guns at wheeling distances, which are reduced to four yards in quarter-column.
Column of fours is the formation adopted for marching along a road and for manoeuvres. Infantry are then four abreast, cavalry eight—i.e. each rank is four horses abreast. In column of sections (the cavalry route formation) the rear rank fours follow behind those of the front rank, instead of marching in line with them. Column of route for artillery and transport is one gun or wagon followed by another at four yards' distance, and so on.
In the United States, besides the column of fours, there is a double column of fours. Other columns are the column by platoons, by companies, the column by divisions (of two companies each), &c.