Ten Biggest Battles of the American Civil War – Second Manassas and Sharpsburg

President Abraham Lincoln and General George Brinton McClellan

Ten Biggest Battles of the Civil War (table)

Eastern Theatre of the Civil War (map)

Second Manassas and Sharpsburg (map)

The second battle of Manassas (2nd Bull Run) on 28th to 30th Aug, fought over substantially the same ground as the war’s first battle, was the largest engagement of the Northern Virginia campaign of the eastern theatre of the Civil War which lasted from mid July to early September of 1862. In total the Union deployed the 78,000 troops of the newly formed Union  Army of Virginia under Gen John Pope, who were opposed by 50,000 men of the Confederate Army of Northern Virginia under Robert E Lee. The campaign is considered as a resounding Confederate victory.

The Army of Virginia had been established by Washington on 26th June 1862, the same day as Lee’s attack at Mechanicsville that began the Seven Days, with Gen John Pope appointed as its commander. Pope was a Mexican war veteran, who had also had a peacetime army career as a topographical engineer. At the outbreak of war he was assigned to the western theatre and despite a personality regarded as prickly and prone to bragging by his subordinates, he enjoyed the confidence of his commanding officer Gen Henry Halleck and led a number of successful actions. As commander of Union Army of the Mississippi, in Feb 1862, he was tasked with clearing Confederate obstacles from the river and as part of the campaign captured the rebel stronghold of New Madrid, Missouri in a surprise attack, then went on to capture the fortress of Island No. 10 on the Kentucky Bend of the great river, taking 12,000 prisoners and opening navigation of the river as far south as Memphis, Tennessee to the Union. For this success, Halleck promoted Pope to Maj Gen and placed him in command of one wing of his own army, then besieging Corinth, Mississippi, when Pope was summoned to Washington to be placed in command of the Army of Virginia.

After the embarrassing defeat of the Peninsula campaign, Lincoln had turned to Pope as a man more inclined to offensive intent than the over-cautious McClellan and tasked him with the defence of Washington and the Shenandoah Valley as well cutting the strategic Virginia Railroad connecting Gordonsville and Lynchburg in order to draw Lee out from the defences of Richmond. Campaigning in the Shenandoah had been in progress for 6 months, with the Confederate forces under the command of Thomas “Stonewall” Jackson, a former mathematics professor. Despite his poor performance in the Seven Days, Jackson had enjoyed huge success in the Shenandoah, where his small force of 17,000 had defended the rich farmlands from three separate Union armies, each larger than his own, totalling  more than 53,000 men. At the battles of Kernstown, Front Royal, Winchester, Cross Keys and Port Republic Jackson’s tiny force had consistently out-fought, out-marched and out-thought the Union forces, inflicting many casualties and stealing so many supplies from the enemy that the commander of the largest Union force, the hapless Gen Nathaniel Banks, was known to the rebel troops as “Quartermaster Banks”.

From an early point in the campaign, Pope showed that he had very different ideas on the prosecution of war from McClellan, believing that the consequences of rebellion should be brought home to civilians found to be aiding or sympathetic to the rebels. He ordered that any house from which shots were fired at Union troops be burned and its occupants taken as POW’s and that his officers be given licence to arrest any male civilian they considered “disloyal”. In addition he ordered that his army subsist from the land when in rebel areas, handing over worthless vouchers in payment, a system that rapidly degenerated into a licence for theft by his men. This caused outrage in the South where the press dubbed him “Miscreant Pope”.

Pope opened the campaign by concentrating his forces near Cedar Mountain, preparing to attack Gordonsville, while Jackson marched from the Valley and attempted to interdict him by occupying Culpepper Courthouse and Lee prepared to take the Army of Northern Virginia north from the defences of Richmond to confront Pope. On the 9th Aug at the battle of Cedar Mountain, 16,000 confederates under Jackson met and defeated 8,000 Union men under Banks, inflicting 2,400 casualties, but had to withdraw to Gordonsville after Pope brought up his main force. On Aug 13th, upon hearing that McClellan was evacuating his force from Harrison’s landing, Lee made his move and advanced to the Rappahannock river in the hope of confronting Pope before McClellan could reinforce him.

As Pope moved south along the Orange and Alexandria railroad to confront Lee, resulting in a series of inconclusive skirmishes around Rappahannock Station, Stonewall succeeded in getting behind Pope’s force and on 27th Aug captured and destroyed the gigantic Union supply depot at Manassas Junction, causing Pope to abruptly disengage and move north to confront him. The following day, the 28th Aug, one whole wing of Lee’s army under Gen James Longstreet, 28,000 strong, attacked the small Union of force of 5,000 guarding Thoroughfare Gap, scattering them and allowing Longstreet to reinforce Stonewall – with dire consequences for Pope as he had now allowed two significant portions of Lee’s army to unite against him.

Two days later, Stonewall made an attempt to lure Pope into battle by attacking part of his army along the Warrenton Turnpike, about two miles to the west of the stone bridge over Bull Run, where the war’s first battle had been fought. As Pope brought up his main force, 62,000 strong, Longstreet approached from Thoroughfare Gap and brought the Confederate force to 50,000 setting the scene for the 2nd battle of Manassas (2nd Bull Run). Jackson deployed along an unfinished railway embankment and prepared for the attack. Unaware of how close Longstreet was, Pope was convinced he had trapped Jackson and launched an assault against the embankment, with heavy losses on both sides. As Longstreet arrived early the afternoon, he threw his 25,000 men against the Union forces recovering from the morning assault against Jackson and sent them reeling back across the old 1st Manassas battlefield and over Bull Run where they established fresh defensive positions. The Union lost 10,000 casualties, against just 1,300 Confederate – a crushing Confederate victory.

Pope withdrew his force to the northeast, concentrating around Centreville, but by Aug 31st, he had lost his nerve and decided to withdraw his army to the defences of Washington until directly ordered by Halleck to attack. Lee however had plans of his own, and on 1st September sent Stonewall and 20,000 men against a force of 8,000 Union men at the battle of Chantilly inflicting 1,500 casualties – including the two Union divisional commanders Philip Kearney and Isaac Stevens who were both killed. This brought to a close the disastrous Northern Virginia campaign, with Pope withdrawing to the defences of Washington under virtual siege. The campaign had cost the Union 16,000 casualties out of 78,000 engaged against 9,000 Confederate out of about 50,000 engaged. Union morale plummeted further after the disaster , whilst Lee’s reputation as a military genius was cemented. Modern scholarship regards the Northern Virginia Campaign as Lee’s finest achievement. Pope was removed from command shortly afterwards, and spent the remainder of the war on the western frontier, out of harm’s way.

Whilst the Union armies failed in the field, Lincoln had political problems of his own. Although an avowed opponent of slavery, he was also a realist. His principal war aim was to re-establish the Union; a precipitous move against slavery might damage the southern economy, but would have dire consequences for his own side too – “I would do it, if I were not afraid that half the officers would fling down their arms and three more states would rise” he said. Nonetheless, in June 1862, on the eve of the Seven Days, Congress, now controlled by the Republicans, outlawed slavery in the western territories, settling the principal issue that had triggered secession in the first place. Lincoln took a secret decision to emancipate all slaves in rebel held areas, believing that such a proclamation would extinguish any remaining support for the Confederacy in Europe, particularly Britain and France. He was persuaded however by his wily Secretary of State William Seward to avoid any public announcement until better news arrived from the battlefield. Unfortunately for Lincoln, there was worse to come. In the western theatre, Braxton Bragg’s Confederate Army of Tennessee had re-invaded Kentucky and attempted to establish a pro-Confederate government at Lexington. Meanwhile Lee, emboldened by his recent success, went on the offensive.

On the 3rd Sept, two days after the Confederate victory at Chantilly , Robert E Lee notified President Davis in Richmond that he intended to invade Maryland and attempt to raise the state for the Confederacy, then capture the rail centre at Harrisburg. The following day 40,000 troops crossed the Potomac at White’s Ford, near Leesburg, into Maryland and headed for the town of Frederick. A Maryland woman watched Lee’s Army of Northern Virginia as they passed – “… the dirtiest men I ever saw … a most ragged, lean and hungry set of wolves. Yet there was a dash about them that our Northern men lacked.”; whilst another wrote “This body of men moved with no order, their guns carried in every fashion, no two men dressed alike, the officers hardly distinguishable from the privates … were these the men who had defeated again and again our splendid legions ?”.

Desperate to get the Army of the Potomac back into the field Lincoln reluctantly turned again to McClellan to take the lead, reasoning that if anyone could get the army back on  its feet again, it was him. The decision was highly controversial however and caused a split in Lincoln’s cabinet, the majority signing a petition opposing the decision; Lincoln, always the pragmatist, felt that he had no choice saying “we must use the tools that we have”.

Despite having only 55,000 men at his disposal, against 90,000 available to McClellan, Lee defied military convention, as he did many times in his career, and split his force by detaching Stonewall to attack the Union ammunition depot at Harper’s Ferry, where in 1858 Lee himself had captured the anti-slavery campaigner John Brown. Deploying 30,000 against just 13,000 defending the town, Jackson forced their surrender after a three day siege, the largest Union surrender of the war. Lee meanwhile had concentrated his remaining force at Hagerstown, 20 miles to the north.

McClellan meanwhile, who had assumed that Lee’s objective must be to swing around to the east and threaten Washington, and was pursuing with his usual excess of caution, was handed the most extraordinary piece of luck. On 13th of September, as Jackson was besieging Harper’s Ferry, the Union commander was handed a piece of paper, found by one of his men in a field near Frederick used by the Confederates as a camp a few days earlier. The paper was wrapped round three cigars, but when opened and read, turned out to be a copy of Lee’s battle plan. At a stroke, McClellan now knew where Lee was headed and that he had split his force into two. “Here is a paper .. “ he told his men “with which if I cannot whip Bobby Lee, I will be willing to go home …”. A similar enthusiastic message was sent to Lincoln promising that he would “send trophies”. Typically for McClellan however, he did nothing for a whole day before finally making his move.

On the 16th of September, Lee with 18,000 of his men, took up defensive positions along a three mile ridge, a few miles to the east of the small town of Sharpsburg, and overlooking a small stream called Antietam Creek. Writing after the war, Lee’s subordinate Gen James Longstreet recalled the day “ … the blue uniforms of the Federals appeared among the trees crowning the heights on the eastern bank of Antietam Creek. The number increased and larger and larger grew the field of blue until it seemed to stretch as far as the eye could see …”. McClellan had brought his main force, 90,000 strong, against Lee’s tiny, divided army. “There was but a single item in our advantage” one of Lee’s aides remembered “ … but it was an important one. McClellan brought superior forces to Sharpsburg, but he also brought himself …”.

Had McClellan hurled his force across the creek that day, the war would have ended there and then, but he did not attack until the following day, believing that he had a least 100,000 men opposing him, giving Lee the chance to order Jackson to force march through the night from Harper’s Ferry and also to call up further troops under Gen Ambrose Powell Hill stationed at Botelers Ford, who would arrive mid way through the following day, more than doubling Lee’s force.

The battle commenced the following morning with an attack against Stonewall’s corps, at the northern end of the Confederate line, with an assault by 9,000 men of Gen Joseph’s Hooker’s corps along the Hagerstown turnpike towards a plateau on which sat a small whitewashed German Baptist chapel named Dunker Church. Seeing the Confederates massed in a cornfield ahead of them, an artillery duel ensued followed by a ferocious hand-to-hand fight in the cornfield before Confederate reinforcements arrived and a back-and- forth duel ensued that lasted all morning and ended in a bloody stalemate. At midday action shifted to the centre of the Confederate line, where 2,500 rebels held a sunken lane against twice that number of Union troops, as another hand to hand fight developed and each side threw in reinforcements until another stalemate ensued.

The final action of the day occurred in the southern section of the battlefield, where Gen Ambrose Burnside and 12,500 men had been ordered to stage a diversionary attack across the creek to coincide with the morning assault in the north, but due to confused orders, Burnside started his attack late. Immediately in front of Burnside’s position was a stone bridge over Antietam Creek, beyond which a small force of Confederate sharpshooters and a few artillery pieces were hiding in woods on a hill overlooking the bridge. Burnside appears not to have known that the creek was only waist deep and could have been forded with ease, instead funnelling his men across the bridge, where the rebels picked them off at will, causing heavy casualties. Eventually, after three separate assaults, sheer weight of numbers told, and the bridge was crossed and the Confederates were pushed back into the town, until AP Hill’s force arrived on the battlefield in the nick of time and stemmed the Union advance. By 18:00 the fighting had died down and Lee’s battered force re-grouped for the final assault that must come the next day – but it never did. McClellan, still convinced that he was outnumbered paused himself and allowed Lee to escape to the south, back across the Potomac. Desperate pleas from Washington to pursue Lee’s broken army were ignored as they “would not be prudent”.

Sharpsburg had 22,800 casualties, not only the single bloodiest day in the civil war, but the single bloodiest day in all US history, before or since. Lincoln held McClellan solely responsible for a stalemate that should have been a decisive victory – despite the huge odds in his favour his excessive caution meant that fully one third of the Union force never fired a shot. Lincoln sacked McClellan, who took no further part in military operations for the remainder of the war. In 1864, he secured the Democrat nomination for the presidential election of that year to stand against him  – a battle which he also lost.

Although a disaster in many ways, Sharpsburg came to be regarded a turning point in the war. It wasn’t the victory that Lincoln was looking for, but it was as much as he was going to get; on 22nd September he issued the Emancipation Proclamation – finally ending any thought in the minds of the British or French governments of any intervention in the war in favour of the Confederacy.



Copyright ©2012 Savereo John

Ten Biggest Battles of the American Civil War

The largest battles of the civil war where approximately the same size as Waterloo (about 200,000), but that doesn’t even make it into the top ten European  battles of the century. The major clashes of the Napoleonic wars and the Franco-Prussian war were all significantly larger than any battle in the American Civil war. The battle of  Sadowa (Königgrätz)  for instance, the decisive engagement of the Austro-Prussian war fought less than a year after the Civil War had 430,000 combatants; that makes it bigger than the Seven Days and Chancellorsville put together. The conflict’s best known battle, Gettysburg, had 170,000 combatants and so was the same size as Austerlitz – although Gettysburg lasted longer, three days whereas Bonaparte needed only eight hours to annihilate Kutuzov in 1805.

Ten Biggest Battles of the Civil War

Location Year Troops Loss % Result
The Seven Days, VA 1862 196,000 18.4% CS Victory
Chancellorsville, VA 1863 195,000 15.5% CS Victory
Fredericksburg, VA 1862 188,000 9.5% CS Victory
Cold Harbor, VA 1864 167,000 10.4% CS Victory
Gettysburg, PA 1863 166,000 27.7% US Victory
Wilderness, VA 1864 163,000 17.6% Draw
Spotsylvania CH, VA 1864 152,000 20.9% Draw
Chickamauga, GA 1863 130,000 27.2% CS Victory
Sharpsburg, MD 1862 114,000 19.9% Draw
2nd Manassas, VA 1862 112,000 16.3% CS Victory

Ive classified the battles by the total number of combatants, and while this is a reasonable enough guide, it can sometimes be misleading. For instance the Siege of Corinth, Mississippi in 1862 had 185,000 combatants, which would have made it fourth on this list, but the majority of these never fired a shot and consequently the casualties were very small (about 1,000 on each side). Ive only included battles were the majority of the forces deployed were actually engaged. Therefore battles like Resaca, Georgia in 1864 and Yorktown, Virginia in 1862 which would have been seventh and eighth on this list, and 3rd Petersburg (tenth) have also been excluded.

Ten Bloodiest Battles by Attrition Rate

Battle Year Combatants Attrition % Outcome
2nd Murfreesboro (Stones River), TN 1863



US Victory
Gettysburg, PA 1863



US Victory
Chickamauga, GA 1863



CS Victory
Shiloh, TN 1862



US Victory
Spotsylvania Courthouse, VA 1864



US Victory
Perryville, KY 1862



CS Victory
Fort Steadman, VA 1865



US Victory
Sharpsburg (Antietam), MD 1862



Wilderness, Virginia 1864



3rd Winchester (Opequon), VA 1864



US Victory

This table shows the ten costliest battles by attrition rate, that is total casualties / total combatants. Ive excluded sieges and other battles where there were instances of mass surrender, ie where most of the “casulaties” were POW’s. Therefore Grant’s victories at Fort Donaldson and Vicksburg, and Stonewall’s capture of Harper’s Ferry are all excluded. On this measure, Rosecran’s victory over Bragg at 2nd Murfreesboro was the costliest battle on this measure, with nearly a third of those engaged as casualties; with Gettysburg and Chickamauga not far behind.

Copyright ©2012 Savereo John