Hooker reported his losses during the campaign at 17,285 men; Lee's loss was 12,277.
If Lee could have attacked Hooker's fleeing columns when they were huddled together at the bridge ends on the river, demoralized and without organization as they were, he might easily have multiplied the Federal loss in killed, wounded, and prisoners by two or three. General Schurz once expressed to the present historian his astonishment that Lee neglected to do this. Perhaps the best answer is given in an extract from Colonel Dodge's exhaustive history of the conflict. He writes that Lee "was doubtless profoundly grateful that the Army of the Potomac should retire across the Rappahannock and leave his troops to the hard-earned rest they needed so much more than ourselves; but little thanks are due to Hooker, who was, it seems, on the north side of the river during these critical moments that the casualties of the campaign were not doubled by a final assault on the part of Lee while we lay in this perilous situation.... Providentially the artillery of the Army of Northern Virginia had expended almost its last round of ammunition previous to this time."
Thus accident alone saved the rear of Hooker's defeated army from a disaster and demoralization comparable with that of Manassas, at a time when, in the urgently expressed opinion of General Sickles, the conspicuous rout of the Army of the Potomac would necessarily have meant the abandonment of the struggle by the North. "If," he alleged, "this army should be destroyed, it would be the last one the country would raise."
Hooker had lost, by his own incapacity, a decisive opportunity to end the war with Federal success, and Lee, because of a lack of ammunition, had lost a still more obvious opportunity to end it by a decisive triumph of the Confederate arms.
When the campaign of Chancellorsville ended in defeat for the Federals, the two armies returned to their former positions at Fredericksburg, confronting each other with a river between--a river which neither of them was for the time being disposed to cross with fighting intent.
Hooker, as his orders issued at that time showed, was content as McClellan had been the year before, that he had saved his great army from disastrous defeat and capture. He was glad to escape with what remained of his army from a position which he had brilliantly achieved in the confident expectation of there completely crushing Lee, compelling his surrender, and marching unopposed into Richmond. His escape had been a very narrow one, made possible only by the exhaustion of the Confederate ammunition, but at any rate he had escaped, and he was disposed to congratulate himself on that.