A considerable force of the enemy was advancing up the turnpike from Fredericksburg, to fall upon his right flank, and upon his rear in case he moved beyond Chancellorsville.  The column was that of General Sedgwick.  This officer, it will be remembered, had been detached to make a heavy demonstration at Fredericksburg, and was still at that point, with his troops drawn up on the southern bank, three miles below the city, on Saturday night, while Jackson was fighting.  On that morning General Hooker had sent for Reynolds’s corps, but, even in the absence of this force, General Sedgwick retained under him about twenty-two thousand men; and this column was now ordered to storm the heights at Fredericksburg, march up the turnpike, and attack Lee in flank.

General Sedgwick received the order at eleven o’clock on Saturday night, about the time when Jackson was carried wounded to the rear.  He immediately made his preparations to obey, and at daylight moved up from below the city to storm the ridge at Marye’s, and march straight upon Chancellorsville.  In the first assaults he failed, suffering considerable loss from the fire of the Southern troops under General Barksdale, commanding the line at that point; but, subsequently forming an assaulting column for a straight rush at the hill, he went forward with impetuosity; drove the Southern advanced line from behind the “stone wall,” which Generals Sumner and Hooker had failed in reaching, and, about eleven in the morning, stormed Marye’s Hill, and killed, captured, or dispersed, the entire Southern force there.  The Confederates fought hand to hand over their guns with the enemy for the possession of the crest, but their numbers were inadequate; the entire surviving force fell back over the Telegraph road southward, and General Sedgwick promptly advanced up the turnpike leading from Fredericksburg to Chancellorsville, to assail General Lee.

It was the intelligence of this threatening movement which now reached Lee, and induced him to defer further attack at the moment upon General Hooker.  He determined promptly to send a force against General Sedgwick, and this resolution seems to have been based upon sound military judgment.  There was little to be feared now from General Hooker, large as the force still was under that officer.  He was paralyzed for the time, and would not probably venture upon any attempt to regain possession of Chancellorsville.  With General Sedgwick it was different.  His column was comparatively fresh, was flushed with victory, and numbered, even after his loss of one thousand, more than twenty thousand men.  Compared with the entire Federal army, this force was merely a detachment, it was true, but it was a detachment numbering as many men, probably, as the effective of Lee’s entire army at Chancellorsville.  He had carried into that fight about thirty-four thousand men.  His losses had been heavy, and the commands were much shaken.  To have advanced under these circumstances upon General Hooker, without regard to General Sedgwick’s twenty thousand troops, inspired by recent victory, would have resulted probably in disaster.