Advancing through a defile.
3. A defile should be passed as quickly as possible, as it is a much more hazardous operation than crossing a bridge. Artillery can seldom be made available till it has passed the defile; whereas it can generally be employed in clearing the opposite bank of a river, previous to the troops pushing across.
Over a bridge.
4. In retreating over a bridge, the artillery will gradually close in from the flanks of the troops, till all the guns are in line in front of the bridge. They will cross by degrees; the flank guns will generally cross under the protection of the centre ones; they may retire limbered up, taking up their position and coming into action to the right and left of the bridge, to protect the centre guns, which will retire with the prolonge and with the largest front possible. They may halt on the highest part, or middle of the bridge, and keep the enemy in check.
Retiring through a defile.
5. A battery should retire from one of its flanks under the protection of the other; the covering guns retiring with the largest front possible.
6. Should the defile be wide, and there are any favourable situations in it, they should be taken advantage of, and guns posted to protect the retreat of the others. The situations must be such as the guns can retire from, and continue the retreat without difficulty.
7. When artillery is retiring along a road, or through a defile which is hilly, some of the guns should halt on the tops of the hills, and protect the retreat of those in the hollow. In these cases, round shot may be fired with safety to the troops retreating, and perhaps with good effect against an enemy.
8. The guns which are retreating, may pass those in position without halting; they will take up other positions, the whole retreating alternately.
9. In retreating towards a defile, the artillery may retire in line, or by half batteries, or by divisions; forming new lines and retreating again; or it may retreat alternately; or in echellon from either flank. This must depend on the nature of the ground, and the flank on which the enemy may be.