Chancellorsville, 1863: A case of nerves, the moon, and mistaken identity

John Lock looks at the Battle of Chancellorsville in 1863 in the first of a series of articles looking at the Butterfly Effect – where small incidents have significant consequences.


WAR: American Civil War
DATE: 2 May 1863

Event: While returning late at night from reconnaissance forward of his lines, Confederate States of America Lieutenant-General Thomas ‘Stonewall’ Jackson, as a result of a friendly fire (fratricide) incident, is shot by his own men and left with a wound that eventually leads to his death eight days later.

Lieutenant-General Thomas ‘Stonewall’ Jackson.

Impact: The Battle of Chancellorsville, considered by many historians to be General Robert E Lee’s greatest victory, was, fundamentally, a direct result of Lee’s risk-taking and Jackson’s aggressive tactics and leadership. It proved, however, a pyrrhic victory given that the South lost one of its greatest, if not most gifted, tactical leaders with the death of Jackson.

Jackson’s death was not only symbolic for the Confederacy, it was more immediately a professional and symbiotic loss for Lee. Having lost one of his two greatest corps commanders, the other being Lieutenant-General James ‘Old Pete’ Longstreet, Lee was forced to divide Jackson’s II Corps after Chancellorsville into two smaller elements: II Corps, commanded by Lieutenant-General Richard S Ewell, and III Corps, commanded by Lieutenant-General Ambrose Powell ‘A P’ Hill.

Less than a month later, during the Battle of Gettysburg, Jackson’s absence was clearly felt. Both Ewell and Hill failed to pursue aggressively their tactical successes throughout the evening of Day 1 of the battle, as Jackson had done at Chancellorsville. These failures would eventually lead to the ill-fated ‘Pickett’s Charge’, and to Lee’s defeat and eventual retreat.

With Jackson’s accidental death, rather than a Confederate victory, Gettysburg became the first clear, major, confidence-boosting victory by the Union’s Army of the Potomac against Lee’s Army of Northern Virginia. This turning-point of the war, the ‘High Tide of the Confederacy’, forced the South’s strategy to shift from offence to defence, changing not only the course of the war, but the course of American history.

Of the millions of bullets fired in the Civil War, only that from the gun of John Wilkes Booth – who assassinated President Abraham Lincoln – can be considered to have had comparable impact.

The butterfly effect

The Butterfly Effect is a metaphor coined in 1972 by Edward Lorenz, an American mathematician, to describe the concept of sensitive and potentially profound dependence on initial conditions in chaos theory – the way a small change at one place in a complex system, such as the beat of butterfly wings, can ultimately, through a series of growing events, have a large impact elsewhere, such as affecting a tornado.

Prussian General Carl von Clausewitz refers in his classic treatise On War to such chaos and complexity as components of the ‘friction’ and ‘fog’ of war. When it comes to Butterfly Effects amid chaos and complexity, where are such history-changing variables more prevalent than on the field of battle?

Thomas Jonathan Jackson was born 1824 in Clarksburg, Virginia (now West Virginia). Almost from birth, Jackson endured a trying childhood of family death, abuse, and poverty. His fortunes took a turn for the better in 1842, when he fortuitously had an opportunity to attend the US Military Academy at West Point. While he struggled initially with the academic load, and was teased by his classmates for his disadvantaged family background and modest education, Jackson, determined to succeed, weathered the hardship and graduated in 1846.

Commissioned a lieutenant of artillery, Jackson went off to fight in the Mexican-American War. Serving with distinction under General Winfield ‘Old Fuss and Feathers’ Scott, he swiftly earned a reputation for courage and tenacity. He participated in a number of campaigns and battles in Mexico, and it was there that Jackson first met then-Captain Robert E Lee, his future commander.

Opposite Thomas ‘Stonewall’ Jackson was probably one of the South’s two greatest generals. Did his accidental death following a friendly-fire incident at the moment of his greatest victory – in partnership with Robert E Lee at Chancellorsville – change the course of the American Civil War? Was this an example of the Butterfly Effect?

Jackson held the rank of brevet major by the war’s close in 1848. In 1851, he resigned his commission and accepted a position at the Virginia Military Institute in Lexington. For the next ten years, Jackson served as a professor of natural and experimental philosophy, as well as artillery tactics. It was Jackson’s desire that Virginia, his home state, should stay in the Union. But, when war finally arrived, he chose his home state when it seceded from the Union in April 1861.

Jackson quickly ascended the ladder of promotion, and, by July, Brigadier-General Jackson was in the thick of the fight during the First Battle of Bull Run (otherwise known as First Manassas).

At a critical moment in the battle, Jackson charged his brigade into a hail of fire to close a gap in the Confederate defensive line in the face of determined Union attack. On observing Jackson’s stand, a fellow brigade commander declared to his brigade, ‘There is Jackson standing like a stone wall… Rally behind the Virginians!’ Rally they did, which led to the South’s first major victory and Jackson’s eternal moniker.

Promoted to major-general in October, Jackson began a series of campaign and battle successes that only enhanced his reputation, starting with his Shenandoah Valley Campaign in the spring of 1862, when he defended western Virginia with an army of 17,000 men against an invading Union force of 60,000.

During the course of the campaign, he and his men earned the title of ‘foot cavalry’ by marching 670 miles in 48 days to fight and win six key battles.

Shortly thereafter, Jackson was ordered to join General Robert E Lee, and he participated in a series of battles including the Seven Days, Cedar Mountain, Second Bull Run (Manassas), Harpers Ferry, and, in mid-September 1862, the ferocious Battle of Antietam (Sharpsburg).

Following Antietam, Lee reorganised his army into two corps, giving Lieutenant-General Stonewall Jackson command of II Corps. In early November, during the Battle of Fredericksburg (11-15 December), Jackson’s greatly outnumbered men were able to hold their lines, contributing substantially to the Confederate victory.

The Battle of Chancellorsville 1-6 May 1863

Following the debacle at Fredericksburg, President Lincoln placed Major-General Joseph ‘Fighting Joe’ Hooker in command of the Army of the Potomac. Hooker immediately reorganised the army and by spring he proclaimed that he had shaped his 134,000 men into ‘the finest army on the planet’.

To defeat Lee, who could field an army of only 61,000 men around Fredericksburg at the time, Hooker devised an elaborate plan of attack.

On 27 April, he began his movements, sending his cavalry force of 10,000 on a mission to manoeuvre behind Lee and cut his lines of communications and supply. He followed that by clandestinely moving his main force of three corps, 70,000 men, across the Rapidan and Rappahannock Rivers above Fredericksburg.

By 30 April, this force was concentrated near the hamlet of Chancellorsville, prepared to attack Lee’s exposed left flank the next morning, while Hooker’s third main element – two corps of infantry (40,000 men) under the overall command of Major-General John Sedgwick – remained in position across from Lee’s forces in Fredericksburg to draw the Confederates’ attention and fix them in position.

Lee, however, did not react as Hooker anticipated. Recognising that he was trapped by significantly larger Union forces in a potential double envelopment from both front and rear, he decided to violate a basic principle of war and divide his small army in the face of a superior enemy. Leaving a modest force of 11,000 men under the command of Major-General Jubal Early to secure Fredericksburg, Lee marched west with the remainder to meet the Union army advancing against his left.

The two armies clashed on 1 May in the vicinity of Chancellorsville. Despite the fierceness of battle and their advantages, by evening the larger Union forces had gained little from the start of the day. That evening, Hooker ordered his army to adopt a defensive posture around the crossroads of Chancellorsville. On his left, Hooker anchored his flank on the Rappahannock River. On his right, however, as a result of a series of mistakes and misunderstandings, the Union flank remained exposed.

Jackson pictured on campaign. He seems to have been one of those men who loved the business of war.

It was late evening when Lee and Jackson met at the intersection of Plank and Furnace Roads to plan the next day’s actions. Seated on a pair of cracker boxes by a campfire and talking late into the night, the two generals, knowing that Hooker’s right flank was in the air, saw an opportunity and planned for Jackson to lead a flanking march to attack the exposed wing. When asked by Lee how many men he would take, Jackson replied, ‘My whole command.’

Departing around 7am that morning, Jackson’s foot cavalry marched for over ten hours to arrive on the Union flank around 5.20pm. With only a few hours of daylight left, Jackson immediately placed two divisions in line. Turning to his lead division commander, he asked, ‘General, are you ready?’ The general nodded. ‘You may go forward then,’ directed Jackson.

Most of the Union soldiers were encamped, unloaded weapons stacked, eating or resting, believing the day’s fighting was done. Suddenly, many were startled by a number of fleeing animals, foxes, and rabbits, bolting out of the woods, shortly followed by musket-fire and the unmistakable ‘Rebel Yell’.

Surprised by the sudden appearance of Jackson’s corps, the ill-led and poorly disciplined Union XI Corps holding the line offered little in the way of organised resistance. Most men fled in mass confusion.

At the Chancellorsville mansion that served as his army’s headquarters, Hooker could hear the sound of gunfire in the distance, followed shortly thereafter by a terrified mass of men and horses stampeding their way across the open clearing near the mansion.

By nightfall, 8pm, the sun had set, and though a full moon soon rose in the clear sky, the thick foliage of the Wilderness was bathed in shadows. Jackson’s men had advanced a mile and a half into the Union’s lines, nearly to Chancellorsville. Halting their attack, the Confederates consolidated their lines in a wide arc perpendicular to Plank Road, a regiment of skirmishers before them, and waited for Jackson’s next orders.

The Butterfly Effect

With a full moon and a partially routed enemy before him, Jackson’s keen tactical sense saw additional opportunity in the midst of the gruesome carnage. To determine his next course of action, he led a group of nine mounted men forward of his lines along Mountain Road, while A P Hill, one of Jackson’s division commanders, led a ten-man group along Plank Road, a parallel trail.

Stopping approximately 200 yards forward, short of his skirmish line, Jackson could hear Union forces not much farther east digging in. He had his answer and turned back, possibly looking to re-enter the lines at a different location than that from which he had departed.

A bit further south down the Confederate line, a lost Union infantry regiment had wandered, undetected by the Confederate skirmishers in front, into the no-man’s land between the skirmishers and the main line. Though a majority of the unit was quickly and quietly captured, their presence, along with other Union activity, had left the Confederates on edge, with itchy trigger fingers.

Shortly after, a lone Union horseman also appeared on the far right of the Confederate line. Already unnerved, the Southerners’ line blindly opened fire. Sequentially, anxious soldiers to their left joined in the firing, creating a cascading wave of musket-fire that thunderously rolled north along the Confederate line towards the 18th North Carolina Regiment.

The men of the 18th were looking to the south-east, directly into a full moon that shone very bright and hung low on the horizon at 25°. The celestial body poured a flood of light from behind Jackson’s and Hill’s mounted groups. Silhouetted in the moonlight, their identities obscured, the two groups were easily mistaken for Union cavalry. In the darkness, the 18th levelled their muskets and fired.

The first volley swept through A P Hill’s party like a scythe, killing or wounding all but Hill. Jackson’s group also took fire, though none were hit initially. A group staff officer, Jackson’s brother-in-law, yelled out, ‘Cease firing! You are firing on your own men!’

In response, an 18th officer shouted, ‘Who gave that order? It’s a lie. Pour it into them boys!’ A second volley thundered, with hundreds of musket-muzzle flashes lighting the darkness.

The Battle of Chancellorsville, 1-6 May 1863, was a military masterpiece in which an army that was outnumbered more than two-to-one divided its forces not once, but twice, in order to deliver a tactical sledge-hammer blow. The partnership between Lee and Jackson was the command pivot on which execution of the plan swivelled. Image: Ian Bull.

Jackson was approximately 90 yards from the closest firers, riding through a thick forest in the dark, a ghostly figure who could most likely only have been seen by a relative few riflemen in the gloomy thickets. Despite the low odds, the second volley killed one and wounded another, while Jackson was struck by three balls – one in the palm of his right hand, a second shattering his lower left arm, and the third, which proved to be the coup de grâce, shattering the bone of his upper left arm, just below the shoulder.

Chaos reigned as horses bolted and enemy artillery, in response to the firing, raked Jackson and his group with cannonballs and canister. Eventually, Jackson’s staff were able to secure and transport the seriously wounded general to a makeshift field hospital at the Wilderness Tavern, where his left arm was amputated just below the shoulder.

Jackson was transported to a second field hospital in Guinea Station, Virginia, on 4 May. Initially, he appeared to be healing, but within days his condition worsened when he developed pneumonia.

On Sunday 10 May 1863, Lieutenant-General Thomas ‘Stonewall’ Jackson, aged 39, died, his final words being, ‘Let us cross over the river and rest under the shade of the trees’, an apparent reference to a beloved childhood place of refuge.


Jackson’s funeral was held in Richmond, where he lay in state while 25,000 mourners filed past in one day to pay their respects. Many placed bouquets of spring flowers at the foot of his catafalque. From this singular event grew the American tradition of funeral flowers.

The Chancellorsville Campaign continued for four more days. A P Hill initially assumed command of II Corps after Jackson’s wounding, but he himself was soon wounded, and command then passed to the cavalry commander Major-General J E B Stuart.

By 6 May, Hooker had had enough. Disengaging his army, he moved his forces back across the river, leaving the field of battle to a victorious Lee.

Despite having been outnumbered more than two to one, Lee had arguably won his greatest victory of the war. However, he paid a terrible price, losing 22% of his force in contrast to Hooker’s 13%.

Aside from the South’s massive casualty list, however, Lee’s greatest loss was that of Stonewall Jackson. Shortly after Jackson’s surgery, Lee had remarked, ‘He has lost his left arm, but I have lost my right.’ History would prove that prophetic.

With Jackson’s loss, Lee was forced to split II Corps into two smaller elements. The Union Army of the Potomac also underwent major change, with Lincoln replacing Hooker with a new commander, Major-General George Meade, just three days prior to the Battle of Gettysburg.

Jackson’s ‘foot cavalry’. Critical to the success of the Confederate plan at Chancellorsville was the speed and surprise achieved in a ten-hour march by Jackson’s 28,000-strong corps.

Gettysburg commenced during the early morning hours of 1 July, when elements of A P Hill’s III Corps were committed on McPherson Ridge in a fight against a cavalry force under the command of Brigadier-General John Buford, an action contrary to Lee’s standing order not to engage in a pitched battle.

The fight raged and grew as more forces were committed on each side. Finally, around mid-afternoon, the Union lines broke, resulting in an uncoordinated retreat, much of it through the streets of Gettysburg, to Cemetery Hill, just south of the town.

Unfortunately for the South, A P Hill missed an excellent opportunity to bolster the confusion and fear in the enemy ranks with an aggressive pursuit by relatively fresh reserves.

Earlier that afternoon, following the death around 10am of the Union’s wing commander, Major-General John Reynolds, on McPherson Ridge, Meade had dispatched his II Corps commander, Major-General Winfield Scott Hancock, to ride ahead without his men to assess the tactical situation and determine if Gettysburg was the place for a major battle. Arriving at Cemetery Hill around 4pm, Hancock quickly assessed the terrain and, following a brief discussion with local commanders, commented, ‘I select this as the battlefield’, and took control of the immediate area to prepare defences.

Lee also understood the advantage that the high ground of Cemetery Hill provided and, around 5pm, ordered Ewell to attack the hill ‘if he found it practicable, but to avoid a general engagement until the arrival of the other divisions of the army’.

The 39-year-old general Thomas Jackson is accidentally shot by his own men on 2 May 1863.

Feeling his men were too battle-fatigued from the day’s fighting to implement the order, Ewell sought assistance from A P Hill, who likewise felt that his corps was too depleted to continue the attack. Unfortunately for Lee, in the end, his order could be perceived as both discretionary and contradictory. Consequently, as the hours slipped into night, the day’s fight ended with Ewell choosing not to attack Cemetery Hill. Throughout the evening and early morning hours of the next day, the Union forces reformed and dug in. Reinforcements arrived, artillery was set up, and the lines continued to expand. By the start of the second day of battle, Lee’s Army of Northern Virginia was facing a partially entrenched Union army that had formed a three-mile long, fishhook-shaped line running from Culp’s Hill on the right flank, along Cemetery Hill and Cemetery Ridge, to the base of Little Round Top. In the end, the Union battlements proved to be insurmountable.

Strategic consequence(s)

Although the first day of battle at Gettysburg was a resounding tactical success for Lee, it was also a day of lost opportunities that could have ended the battle then and there. Had Jackson been present, his impact on any of the three major events that first day would probably have had historic implications.

Would Jackson have obeyed Lee’s standing order to not engage Union forces in a pitched battle, thus avoiding a fight with Buford, which would probably have meant no Battle of Gettysburg at all?

Had Jackson pursued the retreating and disorganised Federal forces through the streets of Gettysburg with his reserves, would the Union have been able to occupy and secure the high ground of Cemetery Hill?

When ordered by Lee to attack Cemetery Hill ‘if he found it practicable’, would Jackson not have swept the enemy from the high ground that first night?

Had either of these last two events occurred, there most likely would not have been a second day of battle at Gettysburg, much less the disastrous third.

Some may question whether Gettysburg was actually the turning-point of the war, given that a strong case can be made, too, for Antietam. Perhaps. But the real significance of Gettysburg is surely that Lee was never able to invade the North again and that the Confederacy thereafter gradually lost all momentum. A revitalised Union army, after so many past failures and disasters, had finally, with no uncertainty, tasted victory against a Lee-led Confederate army that had never before been defeated on the field of battle.

The Union lines at Gettysburg, looking towards the Round Tops. The Union held the high ground at the end of the first day’s fighting because neither of the Confederate corps commanders in action that day, A P Hill and Richard Ewell, pressed home their attacks with vigour. Would the outcome have been different if Jackson had been present?

The Union victory at Gettysburg brought a transformational and galvanising resolve. The confidence of the men of the Army of the Potomac in their commanders soared. It was a confidence gained because Jackson’s replacements had failed to follow orders or take initiatives in the way that Jackson would have done. It was a long-lasting confidence that they could fight and win against the best the Confederacy could throw their way. For Lincoln, the resolve was a political one. Lincoln did not see the national conflict as a ‘Civil War’ but as a ‘War of Rebellion’. As such, he knew the South did not need to win; they just needed to endure, draining the North’s stamina and will. Lincoln understood the ‘awful arithmetic’, the fact that the Union could sustain heavy losses against the Confederacy and still continue to field an army that was a ‘mighty host’. But he also knew that the vast majority of his fellow Northerners did not understand that concept and that a strong, emotional appeal would be required to sustain the national will necessary, despite heavy losses, to secure an eventual Union victory that would maintain a ‘United’ States.

The assassination of President Lincoln by John Wilkes Booth at Ford’s Theatre on 15 April 1865. A distant consequence of Jackson’s accidental death two years earlier?

A little over four months later, Lincoln had the strong, emotional appeal that he needed when he leveraged the battle with his Gettysburg Address, saying, ‘that we here highly resolve that these dead shall not have died in vain, that this nation, under God, shall have a new birth of freedom, and that government of the people, by the people, for the people, shall not perish from the earth’. Lincoln went on to win the 1864 presidential election against an end-the-war Democrat. A single bullet fired on the night of 2 May 1863 perhaps made that possible. In an ironic twist of the Butterfly Effect, had he not won the election, he would not then have faced that other, most-decisive bullet of the American Civil War – the one fired by his assassin, John Wilkes Booth, at Ford’s Theatre on the night of 15 April 1865. •

John D Lock, Lieutenant-Colonel, US Army (ret’d), is a graduate and former assistant professor of the United States Military Academy, West Point. A Ranger-qualified Master Parachutist and honour graduate from many of the Army’s premier leadership courses, his assignments included the 1st Armored and 82nd Airborne Divisions, as well as serving as the chief NATO SFOR engineer in the Balkans during the Kosovo Campaign. Lock is also a published author of works endorsed by the likes of General (ret’d) Colin Powell and Stephen Ambrose.
All images: WIPL, unless otherwise stated.