5. A square should be attacked at one of its angles, which are obviously its weakest and most vulnerable points. But to cover a real attack on an angle, cavalry sometimes makes a false attack on the front of a square.
6. When squares are formed checkerwise, cavalry must attack a flank square, and not expose itself to a cross-fire by charging an interior one.
7. Cavalry charging a square firing irregularly will usually break it. But when the square reserves its fire, and pours in well-aimed volleys at short range, the charge will rarely succeed. The cavalry should, therefore, before charging, use every effort to draw the fire of the square, or of the fronts which threaten it. This is sometimes accomplished by sending forward a few skirmishers to fire on the square.
8. When one square fires to assist another, the firing square should be instantly charged, before it has time to reload.
9. To succeed, a cavalry charge should be made with a desperate, forlorn-hope recklessness, and with reiterated attacks on one point. If the fire has been delivered at very close range, though its effect has probably been destructive, the smoke will momentarily shut out the line of infantry from the horses' view, thus removing the chief obstacle to their breaking through it. The survivors of the fire should therefore rush desperately on.
If the French attacks on the British squares at Quatre Bras had been made in this manner, instead of opening to the right and left, and diverging to a flank at the moment of closing, they would probably have succeeded.
But this sudden divergence is often the fault of the horses, which instinctively recoil before a serried line of infantry, with bayonets at the charge. Cavalry should, therefore, never be practised on the drill-ground in charging a square, as the horses would thereby acquire the habit of suddenly checking their course, or of diverging to a flank, on arriving at the enemy. This would so strengthen their natural instinct that they could never be got to break a square. Or, at least, when this manœuvre is practised for the purpose of instruction, the horses used should never afterwards be taken into the field.
10. The cavalry most formidable to an infantry square are Lancers. Their lances, which are from eleven to sixteen feet long, easily reach and transfix the infantry soldier, while the sabres of the other cavalry are too short to reach him over the horse's neck, and over the musket, lengthened by the bayonet. But Lancers are usually no match against other cavalry, who can parry and ripost before the lance can resume the guard.
11. When cavalry has succeeded in completely breaking a body of infantry, it may often inflict fearful slaughter upon them.
At the battle of Rio Seco, in Spain, after Lasalle's twelve hundred horse had broken the Spanish infantry, they galloped at will among twenty-five thousand soldiers, some five thousand of whom they slew.