The leading columns should always be composed of tried and steady soldiers; and the front of each should invariably consist of the best men in the army.
The advanced and rear guards must be well supported by infantry, with the addition of some light field pieces. The order of battle is so arranged, that the heavy ordnance, the baggage, and the greatest part of the cavalry, which can be of little use on the wings, may be distributed in the centre.
When it is necessary to cross a river, the artillery must be planted directly opposite to the post which the army intends to occupy. Considerable advantage will accrue should the river wind in such a manner as to form a rentrant angle in that particular spot, which advantage would be greatly increased by having a ford near.
In proportion as the construction of the bridge advances, some steady troops must be marched forward, and a regular discharge of musquetry must be kept up against the enemy on the opposite bank.
The instant the bridge is finished, a corps of infantry, with some cavalry, some pieces of artillery, and a certain number of pioneers, to fortify the head of the bridge, must be ordered over. Should there be the least ground to suspect an attack upon the rear guard, the inside tête de pont must also be fortified.
Proper precautions will have been taken to prevent any surprise during the construction of the bridge, and while the troops are crossing. Each side of the river above and below the bridge, will on this account have been well reconnoitred, to ascertain that there are not any armed barges or floating rafters with infernals upon them, kept ready to blow up the bridge, when a considerable part of the army shall have passed the river. If the preservation of the bridge be considered as an object, both ends must be fortified, and adequate guards stationed to defend them.
Each corps that marches separately, such as the advanced and rear guards, and the main body, must be provided with shovels, pick-axes, and a sufficient number of pioneers and guides, to clear the roads, and to direct it on its march.
The following general rules in route marching have been laid down by the celebrated Montecuculli:—
No officer or soldier is on any account to quit his post or rank. The battalion companies must never intermix with the squadrons or troops of cavalry. Squadrons or troops of cavalry must always take care not to leave such wide intervals between them, as will expose them to be suddenly cut off, or such contracted ones as might enable the enemy to throw them into confusion.
In summer, troops should quit their ground or quarters at day-break.