(2.) When preparing for any attack requiring the utmost possible width of front; as where the enemy is to be suddenly surrounded. (3.) When it becomes necessary in order to prevent our troops from being outflanked by the enemy's. (4.) When exposed to continued artillery fire, which is much less destructive on a line than on a column. 6. Cavalry should always present _a front at least equal to the enemy's_; otherwise, its flank, which is cavalry's weak point, will be exposed to attack. When inferior in numbers, we may extend our line by leaving intervals, more or less wide, between its different corps. Any hostile squadrons that may attempt to pass through these intervals to take the line in rear, could be taken care of by the second line. 7. The best formation in respect to _mobility_ is a line of regiments in columns by squadrons, doubled on the centre; corresponding to infantry double columns. 8. The _mixed formation_ of lines and columns is more manageable than simple lines. Which of these two is preferable depends upon the ground, and upon all the other circumstances of the case. 9. The order _in echelons_ is as good in attack as in retreat; since the echelons mutually support each other. 10. Decidedly the most objectionable of all cavalry formations is that in _deep columns_: (1.) From the almost entire loss which it involves of its sabres, which are cavalry's peculiar and most effective weapon. (2.) From the long flanks which it exposes to attack. 11. The formation in _one rank_, instead of two, has been introduced by the new Cavalry Tactics, though it has been as yet but partially adopted in the field. This innovation has two advantages. It doubles the number of sabres to be used against the enemy; and it enables the cavalry to cover double the ground; thus doubling, also, its power to outflank, which is a valuable advantage, especially when opposed to cavalry. Its disadvantage is, that it must, more or less seriously, impair the solidity and vigor of the cavalry charge proper; in which a whole line, with "boot to boot" compactness, comes at once to the shock, like some terrific mechanical engine; and in which the riders in the front rank are compelled to dash on with full speed to the last; knowing that if they slacken rein, even for a moment, they would be ridden over by the rear-rank men one yard behind them. From there being no rear-rank to fill up the gaps caused, during the charge, by the enemy's missiles, or by casualties occasioned by obstacles of the ground, the charging line must generally arrive on the enemy broken and disunited, or as foragers. The moral effect of such a charge on our own men will be unfavorable, as they will not realize the certainty of mutual support at the critical moment; and its moral effect on the enemy must be decidedly inferior to that produced by a charge that is at once swift, solid, and compact.