On Saturday, May 2, 1863, at daylight, or a little before, Lee and Jackson began the execution of their daring stratagem.
Hooker's headquarters were at Chancellorsville. His line stretched eastward and northeastward to the river and westward to a region of high ground unassailable from the front, where his right lay "in the air," in military phrase, that is to say with no natural obstacle, such as a river or a mountain, to defend it. It was Jackson's purpose to march westward on a route parallel with Hooker's line, turn its western end and strike it in flank and rear.
To accomplish that he must completely separate his 22,000 men from Lee's 17,000 and take the chances of battle for a reuniting of the two forces.
It took all day to make the march. All day Jackson kept Stuart's cavalry between his column and the enemy, feeling the enemy's lines to find out how they were posted and what their strength was at every point.
His march was clearly discovered to the Federal troops, and fully reported to their commander, Hooker. But it was completely misinterpreted. It was believed to be the initiatory movement of that retreat upon Richmond, which Hooker—master of logistics that he was—thought that he had by his maneuvers compelled Lee to undertake by way of saving his little army from destruction.
While Jackson, with scarcely any disguise or concealment, was marching along Hooker's front with intent to turn his flank and strike him in rear, Hooker rested easily in the conviction that his adversary, confronted by an irresistible force, was retreating upon Richmond either by way of Culpeper or by the Gordonsville route.
In this belief Hooker broke the continuity of his own lines by throwing forward a part of his forces to assail Jackson's moving column in flank and rear, but he made no effort to advance from Chancellorsville upon Lee's manifestly depleted force in front or in any vigorous way to push a column in between Lee and Jackson. He fought Lee on the skirmish lines all day, but he made no determined attempt to run over the skirmish lines and find out what was behind them. In other words he suffered himself to be completely and disastrously deceived by that tapping at his own lines which Lee ceaselessly kept up by way of misleading him.
As he knew Lee's strength almost to a man, and as he was fully and frequently informed during the day concerning the extent to which Jackson's detachment had weakened it, it is difficult to understand why he did not end the struggle then and there by hurling three men to one against Lee on the one hand and against Jackson on the other, and crushing them separately.
Here was another illustration and proof of the fact that the Federal administration at Washington had not yet found a general fit to command the superb Army of the Potomac. The opportunity at Chancellorsville was the very greatest and completest that was at any time during the war offered to a commanding general on either side to make a quick and complete end of the struggle.
Under like circumstances a Grant or a Sherman would have hurled 40,000 or 50,000 men upon Lee and an equal number upon Jackson, meanwhile employing a lesser but quite sufficient force in keeping the two wings of the Confederate army divided beyond the possibility of reunion. But it is conceivable at least that if Lee had been confronting a Grant or a Sherman, he would never have risked so dangerous a division of his inferior force. The character of the adversary's commanding general is a factor in every military problem, upon which a strategist must reckon as carefully as he does upon the number of that adversary's men or guns.