The reserve of cavalry may be formed in rear of the centre or one of the wings.

In small forces of fifty or sixty thousand men, the cavalry may act with advantage on the wings, in the manner of the ancients.

If the reserve of this arm be large enough to form three separate bodies, it may _itself_ very properly be formed into a centre and wings.

If it be formed into two columns only, they may be placed in rear of the openings between the centre and the wings of the main force.

The reserve of artillery is employed either to reinforce the centre or a wing, and in the defensive is frequently distributed throughout the whole line of battle.