1.  Under ordinary conditions, to expect an army of 45,000 to wrest decisive victory from one of 90,000 well-armed enemies would be to demand an impossibility.  The defence, when two armies are equally matched, is physically stronger than the attack, although we have Napoleon’s word for it that the defence has the harder task.  But that the inherent strength of the defence is so great as to enable the smaller force to annihilate its enemy is contrary to all the teaching of history.  By making good use of favourable ground, or by constructing substantial works, the smaller force may indeed stave off defeat and gain time.  But it can hope for nothing more.  The records of warfare contain no instance, when two armies were of much the same quality, of the smaller army bringing the campaign to a decisive issue by defensive tactics.  Wellington and Lee both fought many defensive battles with inferior forces.  But neither of them, under such conditions, ever achieved the destruction of their enemy.  They fought such battles to gain time, and their hopes soared no higher.  At Talavera, Busaco, Fuentes d’Onor, where the French were superior to the allies, Wellington repulsed the attack, but he did not prevent the defeated armies taking the field again in a few days.  At the Wilderness, Spotsylvania, the North Anna, and Cold Harbour, the great battles of 1864, Lee maintained his ground, but he did not prevent Grant moving round his flank in the direction of Richmond.  At the Second Manassas, Jackson stood fast for the greater part of two days, but he would never have driven Pope across Bull Run without the aid of Longstreet.  Porter at Gaines’ Mill held 55,000 men with 35,000 for more than seven hours, but even if he had maintained his position, the Confederate army would not have become a mob of fugitives.  No; except on peculiarly favourable ground, or when defending an intrenched camp, an army matched with one of equal efficiency and numerically superior, can never hope for decisive success.  So circumstanced, a wise general will rather retreat than fight, and thus save his men for a more favourable opportunity.* (* Before Salamanca, for instance, because Marmont, whose strength was equal to his own, was about to be reinforced by 4000 cavalry, Wellington had determined to retreat.  It is true, however, that when weaker than Massena, whom he had already worsted, by 8000 infantry and 3800 sabres, but somewhat stronger in artillery, he stood to receive attack at Fuentes d’Onor.  Yet Napier declares that it was a very audacious resolution.  The knowledge and experience of the great historian told him that to pit 32,000 Infantry against 40,000 was to trust too much to fortune.)