In establishing the batteries of artillery, in opening roads for their manoeuvres, and in arranging material obstacles for their defence, the axes, picks, and shovels of the sappers are of infinite value.

Fieldworks, bridges, and bridge-defences, frequently have a decisive influence upon the result of a battle, but as these are usually arranged previous to the action, they will be discussed in another place.

In the attack and defence of these field-works, the engineer troops play a distinguished part.

The consideration of this part of the subject, though perhaps properly belonging to the tactics of battles, will also be postponed to another occasion.
We will now discuss the employment of the combined arms on the field of battle.
Before the French Revolution, all the infantry, formed by regiments and brigades, was united in a single body and drawn up in two lines.

The cavalry was placed on the two flanks, and the artillery distributed along the entire line.