Army of the Potomac (USA) (1862 - 1865)

Updated: September 19, 2015

The Army of the Potomac was the Union's primary fighting force in the Eastern Theater throughout most of the American Civil War.

At 4:30 a.m., April 12, 1861, Confederate forces began shelling the Federal garrison at Fort Sumter, South Carolina, plunging the United States into the American Civil War. Three days later President Abraham Lincoln issued a proclamation calling for seventy-five thousand volunteers to suppress the Southern rebellion. On April 25, the first of what would eventually amount to thousands of raw recruits began streaming into Washington, DC. The rapid buildup of local regiments required the United States War Department to quickly create structure out of chaos. By late April, the War Department began organizing the volunteer army into military districts.

On May 27, 1861, the War Department created the Department of Northeastern Virginia, consisting of part of Virginia east of the Allegheny Mountains and north of the James River, except for an area sixty miles around Fort Monroe. The War Department named Brigadier-General Irvin McDowell to command the new department. Believing that Union forces could easily capture the Confederate capital of Richmond, Virginia, President Lincoln and other high-ranking Federal officials urged McDowell to launch an offensive and to bring the rebellion to a swift end. Sensing that his troops were not yet ready for combat, McDowell reluctantly relented to political pressure and marched his soldiers out of Washington, toward Manassas, Virginia, on July 16. On July 21, 1861, the Confederate Army of the Potomac, reinforced by the Army of the Shenandoah, routed McDowell's soldiers at the Battle of Bull Run I, sending the Northerners scurrying back to their defenses near Washington in a disorganized retreat.

One week after the embarrassing defeat, the federal government reorganized its forces near the nation's capital. On July 25, 1861, the War Department merged the Department of Northeastern Virginia with the Department of Washington to create the Division of the Potomac commanded by Major General George B. McClellan. On August 20, McClellan issued General Orders No. 1, assuming "command of the Army of the Potomac, comprising the troops serving in the former departments of Washington and Northeastern Virginia, in the Valley of the Shenandoah, and in the States of Maryland and Delaware." McClellan was not given free reign however. President Lincoln had his own designs. On March 8, 1862 Lincoln issued War Order No. 2, consolidating the Army of the Potomac's divisions into five corps. The President went on to name Major General Irvin McDowell, Brigadier General Edwin V. Sumner, Brigadier General Samuel P. Heintzelman, Brigadier General Erasmus. D. Keyes, and Major general Nathaniel P. Banks to command the five corps, respectively. Dutifully, on March 13, 1862 a disgruntled McClellan issued General Order No. 101 (Army of the Potomac) confirming the Lincoln's selections.

Like McDowell, McClellan was well aware that his army consisted primarily of untrained volunteers. Despite considerable pressure from President Lincoln and other important Federal officials to move against the Confederacy and end the war quickly, McClellan took his time molding the Army of the Potomac into a disciplined fighting force.

Peninsula Campaign

In March 1862, after nearly nine months of preparation, McClellan transported the Army of the Potomac by ship to Fort Monroe in Virginia. With the majority of Rebel forces encamped near Manassas, McClellan planned to march his army up the Virginia Peninsula and to capture the Confederate capital at Richmond. Although he enjoyed a numerical advantage of nearly three-to-one, McClellan advanced cautiously towards Richmond. McClellan’s sluggishness provided General Joseph Johnston with ample time to reinforce the Rebel troops at Richmond. Still, the Army of the Potomac fought its way up the Peninsula to within sight of Richmond. The campaign stalled, however, when General Robert E. Lee assumed command of the forces guarding Richmond, after Johnston was seriously wounded at the Battle of Seven Pines (May 31-June 1, 1862). Lee went on the offensive, launching a series of engagements known as the Seven Days Battles that eventually drove the Army of the Potomac back to the sea, bringing to an end McClellan’s unsuccessful Peninsula Campaign.

Northern Virginia Campaign

After the Army of the Potomac retreated down the Virginia Peninsula, President Lincoln and General-in-Chief-of-the-Army Henry Halleck recalled it to the Washington area on August 3, 1862. With McClellan off of the peninsula, Lee turned his attention to Major General John Pope's Army of Virginia and scored a major victory at the Battle of Bull Run II (August 28 - 30, 1862). Reinforcements from the Army of the Potomac prevented the Union defeat from being worse than it could have been when Pope's army retreated. Lee's victory opened the way for a Confederate invasion of the North.

Maryland Campaign and the Battle of Antietam

After his victory at the Battle of Bull Run II, Robert E. Lee marched the Army of Northern Virginia into Maryland. On September 4, Lee's soldiers began crossing the Potomac River near Poolesville, Maryland. Assuming that the Federal forces near Washington were still in disarray following their stinging defeat at Bull Run, Lee believed that it was safe to temporarily divide his army. The pivotal engagement of the Maryland Campaign occurred near Sharpsburg, Maryland along Antietam Creek. On September 17, 1862, McClellan attacked Lee. During the course of the day, Lee’s divided army reunited on the battlefield and was able to fight the Army of the Potomac to a standoff. The Battle of Antietam ended as a tactical draw, but it was a strategic Union victory because McClellan halted Lee's northern advance. The engagement was the bloodiest single-day of combat during the American Civil War. The Army of the Potomac suffered 12,401 reported casualties, including 2,108 killed. Lee's Army of Northern Virginia suffered 10,316 casualties, including 1,546 killed. Following a day of truce, during which both sides recovered and exchanged their wounded and dead, Lee began withdrawing his army back across the Potomac River, but McClellan failed to press the issue.

Fredericksburg Campaign

Despite the fact that the Army of the Potomac halted Robert E. Lee's advance into Maryland, President Lincoln was disappointed in McClellan's performance, especially the general's reluctance to press Lee's retreating army. On November 5, 1862, Lincoln issued an executive removing McClellan from command of the Army of the Potomac, replacing him with General Ambrose E. Burnside. Lincoln and General-in-Chief Henry Halleck urged Burnside to initiate an invasion of Virginia quickly.

Burnside submitted a proposal to Halleck on November 9. Burnside's plan called for the Army of the Potomac to cross the Rappahannock River at the town of Fredericksburg, to gain control of the Richmond, Fredericksburg and Potomac Railroad, and then to use the railroad for a rapid invasion of Richmond. Halleck and the President approved the proposal. On November 14, Burnside issued General Order No. 184 (AoP), dividing the Army of the Potomac into three "grand divisions." By November 19, 1862, all three grand divisions were poised to cross the Rappahannock.

Unfortunately for Burnside, the pontoon bridges that he planned to use to move his army across the river did not arrive until November 25. By then, Burnside's intentions were clear to Lee, who used the delay to fortify the area around Fredericksburg. Unable to find a suitable alternative site to cross the Rappahannock and feeling pressured by Lincoln and Halleck, Burnside decided to continue the operation and to assault Lee's entrenched army.

On December 13, Burnside began his assault on Lee's army. Troops under the command of Major General Wiliam B. Franklin opened the battle by attacking the Confederate right flank. They experienced some brief success when Major General George Meade's division penetrated Lieutenant General Thomas J. "Stonewall" Jackson's line, but Jackson's men drove Meade back with a counterattack. Burnside next tried attacking Lee's left flank, commanded by Lieutenant General James Longstreet. Having to cross a drainage ditch and an open field under murderous fire from the Rebels, who were well positioned at the base of Marye's Heights above Fredericksburg, sixteen separate Federal charges resulted in a bloodbath. Mercifully, darkness put an end to the killing. Determined to win the battle, Burnside planned another assault for the morning but was finally dissuaded by his officers during the night. Instead, Lee granted Burnside a truce to care for the Union wounded and dead on December 14. The following day, Burnside and his defeated army limped back across the river and the Fredericksburg Campaign ended.

In the aftermath of the Battle of Fredericksburg, President Lincoln came under extreme criticism in the North. Following a second failed offensive, derisively known as the Mud March, in January 1863, Burnside was facing severe criticism from several of his subordinate officers. As accusations intensified, Burnside requested an audience with President Lincoln on January 23, 1863. During the meeting, Burnside presented General Orders No. 8 (Army of the Potomac), which proposed dismissing Major General Joseph Hooker from the army (on approval of the President), and also proposed relieving a large number of Burnside's subordinate general officers of their command. The besieged general proceeded to demand that Lincoln either approve the order or accept Burnside's resignation. Unwilling to authorize a wholesale dismissal of his generals, Lincoln instead drafted General Orders No. 20 (U.S. War Department) on January 25, 1863 announcing that Burnside was being relieved of command of the Army of the Potomac, at his own request. The order went on to name Major General Joseph Hooker as Burnside's successor.

Chancellorsville Campaign

When Hooker assumed command of the Army of the Potomac, morale was sinking, and desertions were rising. Hooker spent his first few months in charge of the army implementing reforms that raised the spirits of his soldiers. On February 5, 1863, Hooker issued General Orders, No. 6 (Army of the Potomac), discontinuing Burnside's Grand Divisions and naming eight corps commanders. By spring, the army was ready for another offensive. Hooker's first test as commander of the army came at the Battle of Chancellorsville (April 30-May 6, 1863), where he proved no match for Robert E. Lee. Despite being outnumbered nearly two to one, Lee out-maneuvered the Federal army and drove the Northerners from the field.

The Confederate victory at Chancellorsville prompted Robert E. Lee to launch a second invasion of the North in June 1863. As Lee moved north, Lincoln ordered Hooker to move in a parallel direction, keeping the Army of the Potomac between Lee and the nation's capital. On June 28, 1863, Hooker attended a strategy meeting with the President and General-in-Chief Henry W. Halleck. When a dispute arose regarding the disposition of troops at Harper's Ferry, Hooker impulsively offered to resign his command. Lincoln quickly accepted the resignation and placed Major General George G. Meade in command of the Army of the Potomac on June 28, 1863.

Gettysburg Campaign

Upon assuming his new command, Meade quickly began moving north from Frederick, Maryland in search of Lee's army in Pennsylvania. When Lee learned of Meade's aggressive pursuit, he ordered his scattered army to concentrate at Cashtown, approximately eight miles west of the village of Gettysburg, Pennsylvania.

On June 30, 1863, Union cavalry commanded by Brigadier-General John Buford entered Gettysburg from the south. Recognizing the strategic importance of the high ground near Gettysburg, Buford ordered his troopers to dismount and to attempt to hold the town until reinforcements arrived. The next morning, Confederate General A. P. Hill sent two brigades into Gettysburg and launched an assault on the Federal cavalry, despite Lee's orders to avoid a general engagement until the Army of Northern Virginia was reunited.

Notwithstanding Lee's wishes, the battle grew in size and intensity. What began as an accidental encounter on July 1 evolved into a full-scale showdown during the next two days. When the fighting ended, sites such as Cemetery Hill, Little Round Top, Devil's Den, the Wheatfield, the Peach Orchard, and Cemetery Ridge were indelibly etched in the annals of American history. Intense combat between the two armies produced between forty-five thousand and fifty-one thousand casualties, including nearly eight thousand dead, making Gettysburg the bloodiest battle of the Civil War. When the fighting came to an end on July 3, the Army of the Potomac had prevailed.

Following the Union victory at Gettysburg, Lee ended his second invasion of the North and withdrew toward Virginia. Despite prodding from his superiors in Washington to aggressively pursue the Confederate army, Meade was initially satisfied with dispatching his cavalry to harass the retreating Grey Coats. Meade had reason to be cautious. The Army of the Potomac was tired and battered from the previous three days of battle. By the time Meade initiated a more aggressive pursuit, Lee was able to cross the Potomac River, bringing an end to the Gettysburg Campaign.

Bristoe Campaign

In September, Confederate officials pressured Lee into sending Lieutenant General James Longstreet's 1st Corps to Chattanooga to reinforce Lieutenant General Braxton Bragg's Army of Tennessee, which was being battered by Major General William Rosecrans's Army of the Cumberland. When Meade learned that Lee had weakened his army, he decided to renew his pursuit. In mid-September, Meade sent two columns forward to engage the remnants of Lee's army, which was encamped along the Rapidan River.

The tables quickly turned, however, when Washington officials ordered Meade's 11th and 12th Corps to Tennessee, under the command of Joseph Hooker, to support the Army of the Cumberland, which was under siege at Chattanooga following the Confederate victory at the Battle of Chickamauga (September 19–20, 1863). Hooker's troops performed well at the Battle of Lookout Mountain (November 24, 1863) and the Battle of Chattanooga (November 23–25, 1863). 

Back in Virginia, with the size of Meade's army also depleted, Lee responded by crossing the Rappahannock River and launching an offensive aimed at Meade's right flank. Meade countered by beginning a withdrawal to secure his supply depot at Centerville.

On October 13, Confederate Major General J.E.B. Stuart's cavalry skirmished with the rearguard of the Union 3rd Corps near Auburn, in Fauquier County, Virginia. On the next day, elements of Confederate General A.P. Hill’s corps were caught in a deadly ambush orchestrated by Major General Gouverneur Warren's 2nd Corps at the Battle of Bristoe Station (October 14, 1863). A futile charge into the murderous fire failed to dislodge the stubborn Yankees. By the time that the Rebels escaped, Hill had lost nearly 1,400 soldiers, as well as a battery of artillery. Following the Union victory at Bristoe Station, Lee called off his short-lived offensive and slowly fell back to the Rappahannock River.

With Lee in retreat, Meade reversed his course and, once again, became the pursuer. On October 19, 1863, Stuart, who was shielding Lee's withdrawal, lured Brigadier-General Judson Kilpatrick's Union cavalry into an ambush near Buckland Mills on a small stream named Broad Run. Stuart's horsemen routed the surprised Blue Coats and sent them fleeing. The Union retreat was so speedy that the Confederates derisively referred to the Battle of Buckland Mills as the Buckland Races. The next day, Stuart's cavalry rejoined Lee's main army.

By early November, the Army of Northern Virginia had safely crossed the Rappahannock River, leaving intact a pontoon bridge at Rappahannock Station. Meade, who was under intense pressure from Washington to continue to pursue Lee's retreating army, launched an attack on November 7, 1863. Lee hastily shifted troops, but failed to halt the Federal advance. At dusk, the Yankees surged forward and overran the Confederates guarding the bridge. During the rout, they captured more than 1,600 soldiers of Major General Jubal Early’s Division. The Union victory at the Battle of Rappahannock Station forced Lee to retreat even farther south than he had hoped before the onset of winter.

Mine Run Campaign

Meade's success at Battle of Rappahannock Station emboldened him to launch another offensive before cold weather arrived. On November 26, 1863, Meade's 2nd, 3rd, and 5th Corps advanced toward the Rapidan River. Meade planned for each of the corps to cross the river and then quickly to swing west in three columns and attack Lee's right flank near Mine Run, a small stream flowing north to the Rapidan. The success of the operation depended upon the element of surprise. Unfortunately for Meade, the weather and some poor generalship combined to eliminate any chance he had to catch Lee off guard. By the time the Union forces were in position to launch their assault, Confederate scouts had discovered their whereabouts. Alerted to the Yankees' presence, Lee quickly dispatched troops to intercept them.

Elements of the two armies collided the next day (November 27) on the east side of Mine Run in a dense tangle of trees and brush locally known as the Wilderness. As both sides hastened to send troops to the front, intense fighting eventually engaged over 16,000 soldiers. After an afternoon of charges and countercharges, neither side could claim a victory when the fighting subsided with the onset of darkness. Veterans on both sides would later recall that day's action as some of the more intense of the entire war.

During the night, Lee pulled his men back to the west side of Mine Run and began digging in. Meade awoke the next morning to find his adversary well entrenched on high ground protected by a stream to his front. After shelling the Confederates for the next two days, while unsuccessfully probing for a weakness in Lee's lines, Meade acquiesced to the futility of launching a hopeless assault against the Rebels. Instead, he wisely turned his army around during the night of December 1-2, and headed north to re-cross the Rapidan. One day later, the Army of the Potomac was safely across the river, and Meade went into winter quarters expecting to be harshly criticized by the northern press and his superiors in Washington for the failed campaign.

Overland Campaign

On March 10, 1864, President Abraham Lincoln appointed Ulysses S. Grant as General-in-Chief of the Armies of the United States. Upon his arrival in Washington, Grant drafted a plan to get the various Union armies in the field to act in concert. He also devised his Overland Campaign to invade east-central Virginia and to destroy the Army of Northern Virginia. Grant set up his headquarters in the field with the Army of the Potomac and instructed General Meade, "Wherever Lee goes, there you will go also."

On May 4, 1864, Grant launched the Overland Campaign, when the Army of the Potomac crossed the Rappahannock and Rapidan Rivers. Understanding that he was better equipped to win a war of attrition, Grant engaged Lee in a series of horrific battles over the next two months. Each side suffered thousands of casualties at the Battle of the Wilderness (May 5-June 24), the Battle of Spotsylvania Court House (May 8-21), the Battle of North Anna (May 23–26), the Battle of Cold Harbor (May 31-June 12), and others during the campaign. After each encounter, Grant ordered Meade to disengage and to march the Army of the Potomac farther south. Forced to stay between Meade and the Confederate capital at Richmond, Lee was compelled to remain one step ahead the Northerners and to continue to absorb damaging body blows from the Army of the Potomac.

The Overland Campaign was a strategic success for the North. By pounding at the Army of Northern Virginia, Grant hindered Southern efforts to send reinforcements to halt Union campaigns elsewhere. In addition, although the Army of the Potomac suffered higher casualties (39,000 to 31,500), the Confederacy was not able to replace their losses as readily. Finally, by threatening Petersburg and, ultimately, Richmond, Grant tied down the Army of Northern Virginia, limiting Lee's military options for the remainder of the war. Despite the strategic success of the Overland Campaign however, it was not without its critics. Shocking casualty rates and grisly battle conditions stunned war-weary Northerners. Some began to refer to Grant as a butcher, whose strategy of winning by attrition exacted too high of a toll in human life.

Petersburg Campaign

On June 12, 1864, Grant abandoned his strategy of attacking Lee's army. He ordered the Army of the Potomac to cross the James River to begin an assault on Petersburg, a crucial supply depot for Richmond and Lee's army, which was located south of the Confederate capital. From June 1864 to March 1865, the Army of the Potomac settled into a strategy of siege warfare. Rather than continue to sacrifice soldiers through head-on engagements with Lee, Grant decided to starve the Army of Northern Virginia, entrenched outside of Petersburg and Richmond into submission by cutting off their supplies. For nine months, the two armies built extensive networks of trenches around Petersburg, as Grant maneuvered his forces around Petersburg to cut off roads and railroads that provided the Confederates with supplies from the south and west. Eventually, the strategy worked. Faced with starvation, Lee was forced to abandon Petersburg on April 2, 1865. The next day, the Confederate government abandoned the capital at Richmond, and Union soldiers occupied the city.

The Petersburg Campaign was a costly but successful Federal offensive. The Union suffered an estimated forty-two thousand casualties, compared with twenty-eight thousand Confederate losses. Despite the heavy casualties, however, Grant achieved his primary objective of forcing Lee to evacuate Petersburg and Richmond.

Appomattox Campaign

After evacuating Petersburg, Lee marched the Army of Northern Virginia west, hoping to find desperately needed supplies at Lynchburg or Danville, Virginia. From there he planned to move south and to unite his army with General Joseph Johnston's forces opposing Major General William T. Sherman in North Carolina. Grant, however, had no intentions of letting Lee's plans come to fruition. Throughout the next week, the Army of the Potomac doggedly pursued Lee's beleaguered army, winning engagements at Sutherland's Station (April 2), Sailor's Creek (April 6), and Appomattox Station (April 8).

On April 7, Grant initiated communications with Lee regarding cessation of hostilities. That night, Lee inquired about "the terms you will offer on condition of its surrender." The next morning, April 8, Grant generously replied, "there is but one condition I would insist upon, – namely that the men and officers surrendered shall be disqualified for taking up arms against the Government of the United States until properly exchanged." He once again invited Lee to meet with him to discuss the surrender of Lee’s army. Lee made one last attempt to escape on April 9, but his forces were defeated at the Battle of Appomattox Court House. That afternoon, he surrendered his army to Grant.

Grand Review and Discontinuation

Following the surrender at Appomattox Court House, most of the Army of the Potomac marched back through eastern Virginia towards Washington, DC. By the morning of May 12, 1865, they established camp at Arlington Heights, just outside of the nation's capital. On the morning of May 23, General Meade paraded his army down Pennsylvania Avenue and through the streets of Washington in front of thousands of citizens, who had assembled to show their gratitude for the service that the soldiers had rendered. The procession eventually passed before a reviewing stand near the White House, where President Andrew Johnson, General-in-Chief Grant, and other government dignitaries saluted the troops, who passed by for over six hours.

On June 28, 1865, General Meade issued General Orders No. 35, announcing that the Army of the Potomac "as an organization, ceases to exist." Troops not "already directed to be mustered out" were consolidated into a provisional corps commanded by Major General Horatio G. Wright for the purpose of initiating their separation from the volunteer army. Over the course of the next few weeks the men of the Army of the Potomac returned to their home states, where they mustered out of service and returned to civilian life.

Ohio Volunteer Infantry Regiments that served with the Army of the Potomac:

4th Regiment Ohio Volunteer Infantry (3 years)
4th Regiment Ohio Volunteer Infantry Battalion
5th Regiment Ohio Volunteer Infantry (3 years)
7th Regiment Ohio Volunteer Infantry (3 years)
8th Regiment Ohio Volunteer Infantry (3 years)
11th Regiment Ohio Volunteer Infantry (3 years)
12th Regiment Ohio Volunteer Infantry (3 years)
23rd Regiment Ohio Volunteer Infantry
25th Regiment Ohio Volunteer Infantry
28th Regiment Ohio Volunteer Infantry
29th Regiment Ohio Volunteer Infantry
30th Regiment Ohio Volunteer Infantry
36th Regiment Ohio Volunteer Infantry
55th Regiment Ohio Volunteer Infantry
60th Regiment Ohio Volunteer Infantry (3 years)
61st Regiment Ohio Volunteer Infantry
62nd Regiment Ohio Volunteer Infantry
66th Regiment Ohio Volunteer Infantry
67th Regiment Ohio Volunteer Infantry
73rd Regiment Ohio Volunteer Infantry
75th Regiment Ohio Volunteer Infantry
82nd Regiment Ohio Volunteer Infantry
107th Regiment Ohio Volunteer Infantry
110th Regiment Ohio Volunteer Infantry
122nd Regiment Ohio Volunteer Infantry
126th Regiment Ohio Volunteer Infantry

Ohio Volunteer Artillery Regiments that served with the Army of the Potomac:

12th Regiment Ohio Volunteer Light Artillery

Ohio Volunteer Cavalry Regiments that served with the Army of the Potomac:

1st Regiment Ohio Volunteer Cavalry
2nd Regiment Ohio Volunteer Cavalry
6th Regiment Ohio Volunteer Cavalry
13th Regiment Ohio Volunteer Cavalry

Cite this Entry

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"Army of the Potomac (USA)," Ohio Civil War Central, 2017, Ohio Civil War Central. 29 Apr 2017 <http://www.ohiocivilwarcentral.com/entry.php?rec=1315>

APA Style

"Army of the Potomac (USA)." (2017) In Ohio Civil War Central, Retrieved April 29, 2017, from Ohio Civil War Central: http://www.ohiocivilwarcentral.com/entry.php?rec=1315

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