So, at Waterloo, Sir Hussey Vivian's brigade of Light Cavalry, which was marching in column by half squadrons, left in front, had begun to form up into line on the leading half squadron, when an order arrived from Wellington to charge. Instantly the charge was made, and, of course, in echelons of half squadrons, extending to the right. The effect of this was that a body of French cavalry on its right, then attacking the British line, was suddenly taken in flank and completely routed. 6. A charge in deep column may sometimes be made necessary by _the nature of the ground_, which, at the same time, protects its long flanks: as where, in our pursuit of the rebels after the battle of Nashville, in 1864, the Fourth United States Cavalry, approaching them over a narrow turnpike, made a vigorous charge in column of fours, which broke their centre, and, with the help of infantry skirmishers on the flanks, drove them from the ground. 7. When the ground is rugged, in order to lessen the number of falls, the rear-rank, in the charge, should _open out six paces_, closing up again at the last moment. 8. Cavalry advances to charge at a _trot_, or at a _gallop_. A fast trot is better than a gallop, as alignments are not easily kept at great speed. Experience has shown that the best distance from the enemy to begin the gallop, is about two hundred and sixty yards; thence steadily increasing to the maximum of speed. This gradual increase of speed is very important, to prevent the horses from being completely blown on reaching the enemy. 9. Cavalry should not charge by _a wood_, till it has been carried by our own infantry, if it can possibly be avoided. At the battle of Kollin, in 1756, Frederick's cavalry, pursuing the Austrians, was taken in flank by some Austrian infantry posted in a wood, and made to retire with great loss. 10. When cavalry is required to charge over unknown ground, it should be preceded by a few men thrown out to the front as skirmishers, in order to _scout the ground_ to be passed over. The neglect of this precaution has sometimes led to great disaster. At Talavera, two cavalry regiments, the First German Hussars and the Twenty-third Light Dragoons, were ordered to charge the head of some French infantry columns. When near the top of their speed they came suddenly upon a deep ravine, with steep sides. Colonel Arentschild commanding the Hussars, who was in front, at once reined up, and halted his regiment, saying: "I vill not kill my young mensch!" But the other regiment, commanded by Colonel Seymour, which was on its left, not seeing the obstacle in time, plunged down it, men and horses rolling over on each other in frightful confusion. Of the survivors, who arrived on the other side by twos and threes, many were killed or taken; and only one-half of the regiment ever returned.