The order of battle is that division and formation of the different arms into separate parts or sections of the whole Army, and that form of general position or disposition of those parts which is to be the norm throughout the whole campaign or war.
It consists, therefore, in a certain measure, of an arithmetical and a geometrical element, the division and the form of disposition. The first proceeds from the permanent peace organisation of the army; adopts as units certain parts, such as battalions, squadrons, and batteries, and with them forms units of a higher order up to the highest of all, the whole army, according to the requirements of predominating circumstances. In like manner, the form of disposition comes from the elementary tactics, in which the army is instructed and exercised in time of peace, which must be looked upon as a property in the troops that cannot be essentially modified at the moment war breaks out, the disposition connects these tactics with the conditions which the use of the troops in war and in large masses demands, and thus it settles in a general way the rule or norm in conformity with which the troops are to be drawn up for battle.
This has been invariably the case when great armies have taken the field, and there have been times when this form was considered as the most essential part of the battle.
In the seventeenth and eighteenth centuries, when the improvements in the firearms of infantry occasioned a great increase of that arm, and allowed of its being deployed in such long thin lines, the order of battle