After a battle, and in the pursuit of a flying enemy, cavalry is invaluable. If Napoleon had possessed a suitable number of mounted troops, with an able commander, at the battles of Lutzen and Ligny, the results of these victories had been decisive; whereas they were really without consequence. On the other hand, the Prussian army in 1806, after the battle of Jena, and Napoleon's army in 1815 at Waterloo, were completely cut to pieces by the skilful use of cavalry in the pursuit of a defeated and dispirited foe. The want of good cavalry was severely felt in the war of the American Revolution. Had Washington possessed a few good squadrons of horse, his surprise and defeat in the lines of Brooklyn, and the consequent loss of New York, had never taken place. The efficient employment of a few good squadrons of cavalry might readily have prevented the defeat at Bladensburg, and the loss of the capitol, in 1814. In a well-organized army, the cavalry should be from one-fourth to one-sixth of the infantry, according to the nature of the war.[32] [Footnote 32: To gain a competent knowledge of the duties connected with the two arms of service mentioned in this chapter, the officer should make himself thoroughly acquainted with Scott's System of Infantry Tactics, for the United States' Infantry, or at least with Major Cooper's abridged edition of Infantry Tactics, and with the system of Cavalry Tactics, adopted in our army; also with the directions for the use of these two arms in a campaign, and their employment on the battle-field, given in the writings of Jomini, Decker, Okouneff, Rocquancourt, and Jacquinot de Presle.] The following books may be referred to for further information respecting the history, organization, use, and instruction of infantry and cavalry:-- _Essai general de tactique._ Guibert. _Considerations generales sur l'infanterie francaise,_ par un general en retraite. A work of merit. _De l'infanterie,_ par l'auteur de l'histoire de l'expedition de Russie. _Histoire de la guerre de la peninsule._ Foy. This work contains many interesting and valuable remarks on the French and English systems of tactics, and particularly on the tactics of Infantry. _Cours d'art et d'histoire militaires._ Jacquinot de Presle. _Art de la guerre._ Rogniat. _Instruction destinee aux troupes legeres,_ &c., redigee sur une instruction de Frederick II. a ses officiers. _English Infantry Regulations._ _Ordonnance_ (French) _pour l'exercice et les manoeuvres de l'infanterie,_ par le commission de manoeuvres. _Aide-memoires des officiers generaux et superieurs, et des capitaines._ _Essai sur l'histoire generale de l'art militaire._ Carion-Nisas. _Histoire de la milice francaise._ Daniel. _Cours elementaire d'art et d'histoire militaires._ Rocquancourt. _Traite elementaire d'art militaire,_ &c. Gay de Vernon. _Introduction a l'etude de l'art de la guerre._ La Roche-Amyou. _Tactique des trois armes._ Decker.