At the battle of Seven Pines, on one occasion, when the rebels were advancing in close columns, they were plied with grape and canister from two of our batteries with but little effect. Every discharge made wide gaps in their leading ranks, but these were instantly filled again, and the columns pressed on. A round-shot, on the other hand, comes shrieking and tearing its way through the entire column, carrying destruction to the very rear-most ranks. The hesitation produced is not limited to the leading ranks, but extends throughout the column. Thus both the actual and the moral effect of ball on a close column is much superior to that of grape or canister. At the bridge of Lodi, the Austrian gunners plied the French column with grape. If they had used round-shot instead, it is doubtful whether Bonaparte would have succeeded in carrying the bridge. 5. But a direct fire with ball on the head of a column of attack would be much assisted by the fire of a few light pieces taking it _in flank_. And, for this fire in flank, case-shot would be powerfully effective; for, from their wide scattering, both their actual and their moral effects would extend through the whole column, from front to rear. 6. A battery with _guns enough to keep up a continuous fire_ has little to fear from an open attack on it by infantry alone. Napoleon observed that no infantry, without artillery, can march one thousand yards on a battery of sixteen guns, well directed and served; for, before clearing two-thirds of the way, they will have been all killed, wounded, or dispersed. This remark was made in reference to smooth-bore guns; the new rifled guns should be still more destructive. 7. _Against skirmishers_, as they offer but a poor mark for ball, grape and canister should alone be used. E. AGAINST CAVALRY. 1. The ground round a battery should be so obstructed as to _prevent the enemy's cavalry from closing on it_; but in the case of a light battery, intended for manoeuvre, so far only as this can be done without impeding the movements of the battery itself. 2. On being threatened by cavalry, a light battery may sometimes promptly change its position to one where the cavalry would attack it _at great disadvantage_. For instance, if posted on an eminence, and cavalry should attempt to carry it by charging up the slope, instead of awaiting the charge in a position which would allow the cavalry to recover breath, and form on the height, it might run its pieces forward to the very brow of the slope, where the cavalry, having lost their impetus, and with their horses blown, would be nearly helpless and easily repulsed. 3. At a distance, the most effective fire on cavalry is with _howitzers_, on account of the terror and confusion caused among the horses by the bursting of the shells. On the cavalry's flanks, when within four hundred or five hundred yards, the fire with grape would be most effective.