The question of the future of cavalry is at present one of great interest among military investigators; for notwithstanding its brilliant achievements during our civil war, the fact is apparent that its sphere has been entirely changed, its old system has become obsolete, and former possibilities no longer lie within its scope. Since Waterloo there had not been, until our war commenced, any opportunity to test the action of cavalry; for its operations in the Crimea and in Italy were insignificant. The art of warfare had, meanwhile, in many respects, become revolutionized by the introduction of rifled arms. Military men waited, therefore, with interest, the experience of the war in this country, to judge from it as to the part cavalry was to perform in future warfare. That experience has shown that the day in which cavalry can successfully charge squares of infantry has passed. When the smooth-bore muskets alone were used by infantry, cavalry could be formed in masses for charging at a distance of five hundred yards; now the formations must be made at the distance of nearly a mile, and that intervening space must be passed at speed under the constant fire of cannon and rifles; when the squares are reached, the horses are frightened and blown, the ranks have been disordered by the impossibility of preserving a correct front during such a length of time at rapid speed, and by the loss of men; the charge breaks weakly on the wall of bayonets, and retires baffled. Infantry, before it learns its own strength and the difficulty of forcing a horse against a bayonet--or rather to trample down a man--has an absurd and unfounded fear of cavalry. This feeling was in part the cause of the panic among our troops at Bull Run--so much had been said about the Black Horse troop of the rebels. The Waterloo achievements of the French were then thought possible of repetition. Now adays it is hardly probable that the veteran infantry of either army would take the trouble to form squares to resist cavalry, but would expect to rout it by firing in line. Neither party in our war has been able to make its mounted forces effective in a general battle. Nothing has occurred to parallel, upon the battle field, those exploits of the cavalry--French, Prussian, and English--in the great wars of the last century, extending to Waterloo.