​Battle of Chancellorsville was Confederates' ‘perfect’ American Civil War victory – but at huge cost

He also boasted, ‘I have the finest army on the planet. I have the finest army the sun ever shone on … If the enemy does not run, God help them. May God have mercy on General Lee, for I will have none.’

Against anyone other than Robert E Lee, his plan might well have been perfect but he was pitting himself against the unrivalled master of manoeuvre warfare.

Chancellorsville is widely regarded as ‘Lee’s perfect battle’ because he defeated a larger enemy through audacious tactics.

Lee disregarded two of the cardinal rules of warfare: not to divide an army in the face of the enemy and not to march an army across the face of an army deployed for battle.

Lee and ‘Stonewall’ Jackson were told by local residents sympathetic to the Confederacy that Hooker’s right flank, unprotected by natural obstacles, was highly vulnerable to attack. J E B Stuart, the Ulster-Scots cavalry commander and ‘the eyes and ears’ of the Army of Northern Virginia, confirmed the accuracy of this intelligence.

Lee, sitting on an empty hardtack box, and Jackson, sitting on a tree stump, brain-stormed how to exploit this weakness in the enemy’s position.

Lee ordered Jackson, who readily concurred, to take his corps along a 12-mile long woodland track through the thickets and bush of the Wilderness, protected from view only by screens of vegetation, and attack the Union right in the rear. This was not a ploy for the faint-hearted.

The rearguard of Jackson’s force was attacked by a Union force commanded by Daniel Sickles but Sickles could not work out the reason for Jackson’s presence in the area because he believed, as did the Union command generally, that the Wilderness was impenetrable.

After many hours moving silently through the Wilderness, Jackson and his men arrived at 5pm just as Union troops were preparing their evening meal, and Jackson ordered his men to attack. One Union soldier recalled that Jackson’s assault came ‘like a clap of thunderstorm from a cloudless sky’.

An aristocratic English journalist and Southern sympathiser, in his account soared to the level of poetry: ‘Swift and sudden as the falcon sweeping on her prey, Jackson had burst on his enemy’s rear and crushed him before resistance could be attempted’. An entire wing of the Union army collapsed.

As the Union troops fled, one of Jackson’s subordinates, complained that the enemy were running too fast and that he couldn’t keep up with them. Jackson shouted back, ‘They never run too fast for me. Press them. Press them.’

Chancellorsville is the perfect example of Lee and his two Ulster-Scots subordinates operating as a formidable team: Stuart providing the intelligence and Jackson executing the plan.

However, should Chancellorsville be viewed as a Pyrrhic victory? If the definition of a Pyrrhic victory is one that inflicts such a devastating toll on the victor that it is a tantamount to defeat or damages long-term progress, the answer is probably yes.

Although Lee defeated an army which outnumbered him two to one, he paid a heavy price. Out of an army of 60,000, he sustained 13,303 casualties (22% of his army) – heavier casualties than he had lost in any previous battle, including even Antietam. Given the limited manpower that the Confederacy could draw upon, these men could not be easily, if at all, replaced.

Was James Longstreet, a capable but admittedly cautious commander, wrong in concluding that Chancellorsville cost the Confederacy more men than it could afford to lose? These losses weakened the Army of Northern Virginia ahead of the invasion of Pennsylvania and the Battle of Gettysburg. Even some of those 13,000 might have made a difference there.

By contrast the Union army of 133,000 sustained over 17,000 casualties but at least they were easily replaceable.

Nevertheless, the Union was shocked by the defeat. President Lincoln thought that the war could have been terminated at Chancellorsville had Hooker managed the battle better.

(To be fair, Hooker’s failure may be partially excused due to a close encounter with a cannonball while standing on the porch of his headquarters. The cannonball struck the wooden column against which he was leaning, knocking him senseless and leaving him concussed. Under these circumstances he ought to have turned over command of his forces to Major-General Couch, his second-in-command, but he declined to do so.)

Lee had a fairly accurate appraisal of the battle: ‘At Chancellorsville we gained another victory; our people were wild with delight – I, on the contrary, was more depressed than after Fredericksburg; our loss was severe, and again we gained not an inch of ground, and the enemy could not be pursued’.

Lee and Jackson’s famous victory also resulted in Jackson’s death.

At dusk on May 2, as Jackson and his escort returned from reconnaissance, for Jackson envisaged an even more comprehensive victory, Confederate pickets mistook them for a detachment of Union cavalry and fired. Two of Jackson’s party were killed. Jackson was hit three times and fell seriously wounded.

As no vital organ had been touched and he had been spared a serious loss of blood, the expectation was that Jackson would lose his left arm but would recover. In a note to Jackson, written on May 4, Lee observed: ‘You are better off than I am, for while you have lost your left, I have lost my right arm.’

However, Jackson was in poor health and contracted pneumonia on May 7 and died on May 10 1863. He was only 39 years old. Deprived of his most consistently aggressive commander, Lee confessed he did not know how to replace him because no other officer could match his tactical genius.