Errors of this nature, however instructive they may be to the student of war, are but spots upon the sun; and in finding in his subordinate such breadth of view and such vigour of execution, Lee was fortunate indeed.  Jackson was no less fortunate when Ashby came under his command.  That dashing captain of free-lances was undoubtedly a most valuable colleague.  It was something to have a cavalry leader who could not only fight and reconnoitre, but who had sagacity enough to divine the enemy’s intentions.  But the ideas that governed the employment of the cavalry were Jackson’s alone.  He it was who placed the squadrons across Fremont’s road from Wardensville, who ordered the demonstrations against Banks, before both M’Dowell and Front Royal, and those which caused Fremont to retreat after Port Republic.  More admirable still was the quickness with which he recognised the use that might be made of mounted riflemen.  From the Potomac to Port Republic his horsemen covered his retreat, dismounting behind every stream and along the borders of every wood, checking the pursuers with their fire, compelling them to deploy their infantry, and then retreating rapidly to the next position.  Day after day were the Federal advanced guards held in check, their columns delayed, and the generals irritated by their slippery foe.  Meanwhile, the Confederate infantry, falling back at their leisure, were relieved of all annoyance.  And if the cavalry was suddenly driven in, support was invariably at hand, and a compact brigade of infantry, supported by artillery, sent the pursuing horsemen to the right-about.  The retreat of the Valley army was managed with the same skill as its advance, and the rear-guard tactics of the campaign are no less remarkable than those of the attack.

To judge from the Valley campaign, Jackson handled his horsemen with more skill than any other commander, Confederate or Federal.  A cavalry that could defend itself on foot as well as charge in the saddle was practically a new arm, of far greater efficiency than cavalry of the old type, and Jackson at once recognised, not only its value; but the manner in which it could be most effectively employed.  He was not led away by the specious advantages, so eagerly urged by young and ambitious soldiers, of the so-called raids.  Even Lee himself, cool-headed as he was, appears to have been fascinated by the idea of throwing a great body of horsemen across his enemy’s communications, spreading terror amongst his supply trains, cutting his telegraphs, and destroying his magazines.  In hardly a single instance did such expeditions inflict more than temporary discomfort on the enemy; and the armies were led more than once into false manoeuvres, for want of the information which only the cavalry could supply.  Lee at Malvern Hill and Gettysburg, Hooker at Chancellorsville, Grant at Spotsylvania, owed defeat, in great measure, to the absence of their mounted troops.  In the Valley, on the contrary, success was made possible because the cavalry was kept to its legitimate duty—­that is, to procure information, to screen all movements, to take part in battle at the decisive moment, and to carry out the pursuit.