The Cavalry Corps, except Pleasonton's brigade, which accompanied Hooker's headquarters during this movement, left on the 13th. On the 15th Stoneman threw a division across the river at Rappahannock station, where the Orange and Alexandria Railroad crosses the river. But a sudden rise in consequence of heavy rains obliged this division to return by swimming the horses. Gen. Lee says, referring to this check, that "their efforts to establish themselves on the south side of the river were successfully resisted by Stuart." But the rise in the river was the actual cause. There was no crossing of swords. At the time the cavalry marched, an infantry brigade and a battery were sent to Kelley's Ford, and a regiment to United-States Ford, to hold these crossings against scouting parties, or any counter-demonstration on the part of the enemy. The river did not fall so that Stoneman could pass at that point until the 27th, when it was too late to accomplish valuable results under the orders of the 12th; for the whole army was now on the march. Between the 15th and 27th the cavalry, under instructions from Hooker, remained in camp along the Orange and Alexandria Railroad. It has, however, never been satisfactorily explained why it might not have crossed higher up, and have utilized these precious two weeks. It could not have been of less use than it was, and might possibly have been able to call Stuart's entire force away from Lee's army. Nor was it impossible, in part at least, to do the work cut out for it. Even to threaten Lee's communications would have seriously affected the singleness of purpose he displayed in this campaign. But the operations of Stoneman, as they had no effect whatever upon the manoeuvres of either Lee or Hooker, may be treated of separately, as a matter almost apart from the one under consideration. And thus, in the failure of the cavalry raid, miscarried the first effort of this ill-fated campaign. It is not often that the danger of detaching the entire cavalry force of an army, for service at a distance from its infantry corps, is illustrated in so marked a manner as it was on this occasion. Hooker left himself but a small brigade, of four regiments and a horse-battery, to do the scouting for an army of over one hundred thousand men. Had he retained a sufficient force to march with the main body, there would no doubt have been at least a brigade of it, instead of a few scouts, sent out to near Old Wilderness Tavern and along the Orange plank road to the junction of the Brock road. Jackson's movements would then have been fully known. The bulk of the cavalry of an army should be with the infantry corps when in the presence of the enemy. For cavalry are the antennae of an army. VII. THE FEINT BY THE LEFT WING.