The force of this arm depends upon the rapidity and accuracy of its fire; rash valor is therefore far less desirable in artillery than skill, patience, and cool courage. Artillery always acts at a distance, and in mass; single pieces are seldom employed, except to cover reconnoitring parties, or to sustain the light infantry in a skirmish. Mounted batteries sometimes approach within two or three hundred yards of the enemy's infantry; but this is only done with a strong support of other troops, and to prepare the way for a charge of cavalry. The batteries do not accompany the charge, but they should always follow up and complete the success; mounted batteries are particularly useful in pursuit. If Murat, in 1812, had accompanied his attacks upon Neveroffskoi's retreating columns of sixty thousand infantry by two or three batteries of mounted artillery, the whole column must have been captured or destroyed. Artillery, on the field of battle, is very liable to allow its fire to be drawn, and its projectiles wasted, while the enemy is at too great a distance to be reached. It is a very common thing in a battle, to employ two or three pieces of heavy calibre at the beginning of the fight, in order to provoke the opposing batteries to open their fire before the proper time. The waste of material is not the only loss attending this error; the troops are fatigued and disheartened, while the courage and confidence of their opponents are always revived by a weak and inaccurate fire. To avoid such an error the commanding officer of a battery of artillery should be perfectly familiar with the effective ranges of his pieces, and accustomed to form a correct estimate of distances. For this purpose the eye should be frequently practised in time of peace in estimating the ranges for different calibres. The effective range of a 12-pounder field-piece is about . . . . . . 1000 yds. " " " " 6 " " 800 " " " " " 24 " howitzer, 600 " " " " " 12 " " 500 " " " " " grape and case shot is from . . . . . . 300 to 500 " Even at these distances the aim is usually so inaccurate that a large portion of the projectiles are lost. In the attack on Spires, a whole column of artillery expended its fire while at a distance of 900 yards from the enemy, who, of course, received little or no injury. In firing from fortifications, the aim is far more accurate, and the artillery may therefore be employed to advantage as soon as the enemy comes within the longest range. II. As an arm of succor, the artillery serves, 1st, to give impulsive force to the attacking columns; 2d, to assist in arresting, or at least in retarding, the offensive movements of an enemy; 3d, to protect the avenues of approach, and to defend obstacles that cover a position; and, 4th, to cover a retrograde movement.