(2.) It must not be posted on the very ground it is to defend, but in rear of it; as it acts effectively only by its charge.
Attacking cavalry must have favorable ground in front; defending cavalry, in rear. An obstacle in either case may be fatal.
IV.—Its Supports.
1. The flanks of cavalry lines or columns are always exposed. They should, therefore, be protected by supports of light cavalry, which can act promptly and swiftly. When behind a line, these supports should be usually in open column, so as to be able to wheel, without a moment's delay, into line.
2. The most effectual mode of protecting the flank of a line or column of cavalry is by means of squadrons in rear, formed in echelons extending outwards; as this exposes the enemy's cavalry that may attempt to charge the main body in flank to be immediately charged in flank themselves; which would be destruction. For this purpose, irregular cavalry may be as effective as any other.
3. This cavalry support or reserve behind the flanks may sometimes play an important offensive part. The enemy's first line, the instant after either making or receiving a charge, is always in greater or less disorder; and a vigorous charge then made on it in flank by our own flank reserve, would have a decisive effect.
4. Cavalry should never engage without a support or reserve in rear, not only to guard its flanks, but also to support it when disorganized by a successful charge.
5. So, when engaged in skirmishing order, being then very much exposed, it must always be protected, like infantry skirmishers, by supports in close order.
6. It has been already seen that, although cavalry may carry a position, it cannot hold it, if attacked by infantry. When used for such a purpose, therefore, it should always be accompanied by an infantry support.
The French cavalry succeeded in carrying the plateau of Quatre Bras; but, having no infantry with it to reply to the terrible fire of the Allied infantry from the surrounding houses, it was compelled to retire, and yield it again to the enemy.