On the 4th of May the Army of the Potomac moved against Lee, who was occupying a defensive position on the south bank of the Rapidan. After detailing the various detachments which I was obliged to supply for escorts and other mounted duty, I crossed the river with an effective force of about 10,000 troopers. In the interval succeeding my assignment to the command of the cavalry, I had taken the pains to study carefully the topography of the country in eastern Virginia, and felt convinced that, under the policy Meade intended I should follow, there would be little opportunity for mounted troops to acquit themselves well in a region so thickly wooded, and traversed by so many almost parallel streams; but conscious that he would be compelled sooner or later either to change his mind or partially give way to the pressure of events, I entered on the campaign with the loyal determination to aid zealously in all its plans.

General Lee's army was located in its winter quarters behind intrenchments that lay along the Rapidan for a distance of about twenty miles; extending from Barnett's to Morton's ford. The fords below Morton's were watched by a few small detachments of Confederate cavalry, the main body of which, however, was encamped below Hamilton's crossing, where it could draw supplies from the rich country along the Rappahannock. Only a few brigades of Lee's infantry guarded the works along the river, the bulk of it being so situated that it could be thrown to either flank toward which the Union troops approached.

General Grant adopted the plan of moving by his left flank, with the purpose of compelling Lee to come out from behind his intrenchments along Mine Run and fight on equal terms. Grant knew well the character of country through which he would have to pass, but he was confident that the difficulties of operation in the thickly wooded region of the Wilderness would be counterbalanced by the facility with which his position would enable him to secure a new base; and by the fact that as he would thus cover Washington, there would be little or no necessity for the authorities there to detach from his force at some inopportune moment for the protection of that city.

In the move forward two divisions of my cavalry took the advance, Gregg crossing the Rapidan at Ely's ford and Wilson at Germania ford. Torbert's division remained in the rear to cover the trains and reserve artillery, holding from Rapidan Station to Culpeper, and thence through Stevensburg to the Rappahannock River. Gregg crossed the Rapidan before daylight, in advance of the Second Corps, and when the latter reached Ely's ford, he pushed on to Chancellorsville; Wilson preceded the Fifth Corps to Germania ford, and when it reached the river he made the crossing and moved rapidly by Wilderness Tavern, as far as Parker's Store, from which point he sent a heavy reconnoissance toward Mine Run, the rest of his division bivouacking in a strong position. I myself proceeded to Chancellorsville and fixed my headquarters at that place, whereon the 5th I was joined by Torbert's division.

Meanwhile, General Meade had crossed the Rapidan and established his headquarters not far from Germania ford. From that point he was in direct communication with Wilson, whose original instructions from me carried him only as far as Parker's Store, but it being found, during the night of the 4th, that the enemy was apparently unacquainted with the occurrences of the day, Meade directed Wilson to advance in the direction of Craig's Meeting House; leaving one regiment to hold Parker's Store. Wilson with the second brigade encountered Rosser's brigade of cavalry just beyond the Meeting House, and drove it back rapidly a distance of about two miles, holding it there till noon, while his first brigade was halted on the north side of Robinson's Run near the junction of the Catharpen and Parker's Store roads.

Up to this time Wilson had heard nothing of the approach of the Fifth Corps, and the situation becoming threatening, he withdrew the second brigade to the position occupied by the first, but scarcely had he done so when he learned that at an early hour in the forenoon the enemy's infantry had appeared in his rear at Parker's Store and cut off his communication with General Meade. Surprised at this, he determined to withdraw to Todd's Tavern, but before his resolution could be put into execution the Confederates attacked him with a heavy force, and at the same time began pushing troops down the Catharpen road. Wilson was now in a perplexing situation, sandwiched between the Confederates who had cut him off in the rear at Parker's store and those occupying the Catharpen road, but he extricated his command by passing it around the latter force, and reached Todd's Tavern by crossing the Po River at Corbin's bridge. General Meade discovering that the enemy had interposed at Parker's store between Wilson and the Fifth Corps, sent me word to go to Wilson's relief, and this was the first intimation I received that Wilson had been pushed out so far, but, surmising that he would retire in the direction of Todd's Tavern I immediately despatched Gregg's division there to his relief. Just beyond Todd's Tavern Gregg met Wilson, who was now being followed by the enemy's cavalry. The pursuing force was soon checked, and then driven back to Shady Grove Church, while Wilson's troops fell in behind Gregg's line, somewhat the worse for their morning's adventure.

When the Army of the Potomac commenced crossing the Rapidan on the 4th, General J. E. B. Stuart, commanding the Confederate cavalry, began concentrating his command on the right of Lee's infantry, bringing it from Hamilton's crossing and other points where it had been wintering. Stuart's force at this date was a little more than eight thousand men, organized in two divisions, commanded by Generals Wade Hampton and Fitzhugh Lee. Hampton's division was composed of three brigades, commanded by Generals Cordon, Young, and Rosser; Fitzhugh Lee's division comprised three brigades also, Generals W. H. F. Lee, Lomax, and Wickham commanding them.

Information of this concentration, and of the additional fact that the enemy's cavalry about Hamilton's crossing was all being drawn in, reached me on the 5th, which obviated all necessity for my moving on that point as I intended at the onset of the campaign. The responsibility for the safety of our trains and of the left flank of the army still continued, however, so I made such dispositions of my troops as to secure these objects by holding the line of the Brock road beyond the Furnaces, and thence around to Todd's Tavern and Piney Branch Church. On the 6th, through some false information, General Meade became alarmed about his left flank, and sent me the following note:


"HEADQUARTERS ARMY OF THE POTOMAC,
"May 6, 1864.—1 o'clock P. M.
"MAJOR-GENERAL SHERIDAN,
"Commanding Cavalry Corps
"Your despatch of 11.45 a.m., received. General Hancock has been heavily pressed, and his left turned. The major-general commanding thinks that you had better draw in your cavalry, so as to secure the protection of the trains. The order requiring an escort for the wagons to-night has been rescinded.
"A. A. HUMPHREYS,
"Major-General, Chief-of-Staff."

On the morning of the 6th Custer's and Devin's brigades had been severely engaged at the Furnaces before I received the above note. They had been most successful in repulsing the enemy's attacks, however, and I felt that the line taken up could be held; but the despatch from General Humphreys was alarming, so I drew all the cavalry close in toward Chancellorsville. It was found later that Hancock's left had not been turned, and the points thus abandoned had to be regained at a heavy cost in killed and wounded, to both the cavalry and the infantry.