4. The _last discharge_ should be of canister alone, and made by all the pieces at once, when the battery should be swiftly withdrawn. 5. If the cavalry succeed in reaching the pieces before their withdrawal, the gunners may find temporary refuge _under the carriages_. F. AGAINST ARTILLERY. 1. As guns in the field should generally play on troops instead of batteries, there should be a _reserve of horse artillery_ to take the enemy's batteries in flank, in case of need, as well as for other purposes. 2. Though the ordinary use of artillery is against infantry and cavalry only, special circumstances may render it expedient that a certain portion of it should _respond to the enemy's batteries_. In this case, not over one-third should be used for that purpose. 3. When we have _guns in abundance_, it might be sometimes advisable, by using several batteries at once, to silence the enemy's guns, before beginning to play on his troops. 4. Artillery properly plays on the enemy's _guns_-- (1.) At the moment of their coming into action, for then they are so exposed that our fire will be peculiarly effective, and perhaps to such a degree as to prevent their opening on us. (2.) When our troops move forward to attack, in order to draw away from them the fire of the enemy's batteries, or, at least, to render it unsteady, inaccurate, and ineffective; and (3.) Generally, when his guns are causing us very great damage. 5. _Against guns_, solid shot or shells only should be used, since they alone are capable of inflicting any serious injury on either guns or their carriages: solid shot, by their great weight and momentum; shells, by their bursting. But within three hundred or four hundred yards, grape and canister would soon destroy the gunners and the horses. 6. Our fire on a hostile battery would not only be very effective when it is coming into action, but at all other times _when its flanks are exposed_; as in limbering up to move off, or in a flank march. On these occasions we should use grape, if near enough; otherwise, spherical case would be generally the best. 7. When possible to avoid it, _a field battery should not be opposed to a battery of position_, or, generally, a battery of light guns to one of heavy guns. For even when the numbers of pieces on the two sides are equal, the enemy's superiority in range and in weight of metal would give him such advantage in the duel that our own battery would soon be destroyed or silenced. VI.--Its Fire. 1. It is important not to commence the fire till our guns are in _sure range_-- (1.) Because a harmless fire serves but to embolden the enemy and discourage our own troops. (2.) Because artillery ammunition should never be wasted. The fate of a battle will sometimes depend on there being a sufficient supply of it at a particular moment. 2. The usual maximum distances at which smooth-bore field guns may open fire _with any considerable effect_, are--