|Army of the Potomac|
|Founded||July 26, 1861|
|Disbanded||June 28, 1865|
|Branch||United States Army|
|Role||Primary Union Army in Eastern Theater|
|Part of||Union Army|
|Engagements||American Civil War|
| George B. McClellan |
George G. Meade
The Army of the Potomac was the principal Union Army in the Eastern Theater of the American Civil War. It was created in July 1861 shortly after the First Battle of Bull Run and was disbanded in June 1865 following the surrender of the Confederate Army of Northern Virginia in April.
The Army of the Potomac was created in 1861 but was then only the size of a corps (relative to the size of Union armies later in the war). Its nucleus was called the Army of Northeastern Virginia, under Brig. Gen. Irvin McDowell, and it was the army that fought (and lost) the war's first major battle, the First Battle of Bull Run. The arrival in Washington, D.C., of Maj. Gen. George B. McClellan dramatically changed the makeup of that army. McClellan's original assignment was to command the Division of the Potomac, which included the Department of Northeast Virginia under McDowell and the Department of Washington under Brig. Gen. Joseph K. Mansfield. On July 26, 1861, the Department of the Shenandoah, commanded by Maj. Gen. Nathaniel P. Banks, was merged with McClellan's departments and on that day, McClellan formed the Army of the Potomac, which was composed of all military forces in the former Departments of Northeastern Virginia, Washington, Pennsylvania, and the Shenandoah. The men under Banks's command became an infantry division in the Army of the Potomac.The army started with four corps, but these were divided during the Peninsula Campaign to produce two more. After the Second Battle of Bull Run, the Army of the Potomac absorbed the units that had served under Maj. Gen. John Pope.
It is a popular, but mistaken, belief that John Pope commanded the Army of the Potomac in the summer of 1862 after McClellan's unsuccessful Peninsula Campaign. On the contrary, Pope's army consisted of different units, and was named the Army of Virginia. During the time that the Army of Virginia existed, the Army of the Potomac was headquartered on the Virginia Peninsula, and then outside Washington, D.C., with McClellan still in command, although three corps of the Army of the Potomac were sent to northern Virginia and were under Pope's operational control during the Northern Virginia Campaign.
The Army of the Potomac underwent many structural changes during its existence. The army was divided by Ambrose Burnside into three grand divisions of two corps each with a Reserve composed of two more. Hooker abolished the grand divisions. Thereafter the individual corps, seven of which remained in Virginia, reported directly to army headquarters. Hooker also created a Cavalry Corps by combining units that previously had served as smaller formations. In late 1863, two corps were sent West, and— in 1864— the remaining five corps were recombined into three. Burnside's IX Corps, which accompanied the army at the start of Ulysses S. Grant's Overland Campaign, rejoined the army later. For more detail, see the section Corps below.
The Army of the Potomac fought in most of the Eastern Theater campaigns, primarily in (Eastern) Virginia, Maryland, and Pennsylvania. After the end of the war, it was disbanded on June 28, 1865, shortly following its participation in the Grand Review of the Armies.
The Army of the Potomac was also the name given to General P. G. T. Beauregard's Confederate army during the early stages of the war (namely, First Bull Run; thus, the losing Union Army ended up adopting the name of the winning Confederate army). However, the name was eventually changed to the Army of Northern Virginia, which became famous under General Robert E. Lee.
In 1869 the Society of the Army of the Potomac was formed as a veterans association. It had its last reunion in 1929.
Because of its proximity to the large cities of the North, such as Washington, D.C., Philadelphia, and New York City, the Army of the Potomac received more contemporary media coverage than the other Union field armies. Such coverage produced fame for a number of this army's units. Individual brigades, such as the Irish Brigade, the Philadelphia Brigade, the First New Jersey Brigade, the Vermont Brigade, and the Iron Brigade, all became well known to the general public, both during the Civil War and afterward.
The army originally consisted of fifteen divisions, the Artillery Reserve and the Cavalry Command. Commanded by Edwin V. Sumner, William B. Franklin, Louis Blenker, Nathaniel P. Banks, Frederick W. Lander (Replaced by James Shields after Lander's death on March 2, 1862, Silas Casey, Irvin McDowell, Fitz John Porter, Samuel P. Heintzelman, Don Carlos Buell (Replaced by Erasmus D. Keyes in November, 1861), William F. Smith, Joseph Hooker, John A. Dix, Charles P. Stone (Replaced by John Sedgwick in February, 1862), George A. McCall, George Stoneman (Replaced by Philip St. George Cooke in January, 1862) and Henry J. Hunt. Because this arrangement would be too hard to control in battle, President Lincoln issued an order on March 13, 1862, dividing the army into five corps headed by MG Irvin McDowell (I Corps; Franklin's Division: BG William B. Franklin, McCall's "Pennsylvania Reserves" Division: BG George A. McCall and McDowell's old Division under BG Rufus King.), BG Edwin V. Sumner (II Corps; Sumner's old Division under BG Israel B. Richardson, Sedgwick's Division: BG John Sedgwick and Blenker's Division: Louis Blenker.), BG Samuel P. Heintzelman (III Corps; Porter's Division: BG Fitz John Porter, Hooker's Division: BG Joseph Hooker and Heintzelman's old Division under BG Charles S. Hamilton), BG Erasmus D. Keyes (IV Corps; Keyes' old Division under BG Darius N. Couch, Smith's Division: BG William F. Smith and Casey's Division: BG Silas Casey), MG Nathaniel P. Banks (V Corps would later become the XII Corps; Banks' old Division under BG Alpheus S. Williams, Shield's Division: BG James Shields and a Cavalry Division under BG John P. Hatch). The five highest-ranking officers division commanders in the army, McClellan was not happy with this, as he had intended to wait until the army had been tested in battle before judging which generals were suitable for corps command.
After the Battle of Williamsburg on May 5, McClellan requested and obtained permission to create two additions corps; these became the V Corps, headed by BG Fitz-John Porter, and the VI Corps, headed by BG William B. Franklin, both personal favorites of his. After the Battle of Kernstown in the Valley on March 23, the administration became paranoid about "Stonewall" Jackson's activities there and the potential danger they posed to Washington D.C., and to McClellan's displeasure, detached Blenker's division from the II Corps and sent it to West Virginia to serve under John C. Fremont's command. McDowell's corps was detached as well and stationed in the Rappahannock area.
In June 1862, George McCall's division from McDowell's corps (the Pennsylvania Reserves Division) was sent down to the Peninsula and temporarily attached to the V Corps. In the Seven Days Battles, the V Corps was heavily engaged. The Pennsylvania Reserves, in particular, suffered heavy losses including its division commander, who was captured by the Confederates, and two of its three brigadiers (John F. Reynolds, also captured, and George Meade, who was wounded). The III Corps fought at Glendale, however, the rest of the army was not heavily engaged in the week-long fight aside from Slocum's division of the VI Corps, which was sent to reinforce the V Corps at Gaines Mill.
The Army of the Potomac remained on the Virginia Peninsula until August, when it was recalled back to Washington D.C. Keyes and one of the two IV Corps divisions were left behind permanently as part of the newly created Department of the James, while the other division, commanded by Brig. Gen Darius Couch was attached to the VI Corps.
During the Second Battle of Bull Run, the III and V Corps were temporarily attached to Pope's army; the former suffered major losses and was sent back to Washington to rest and refit afterward, so it did not participate in the Maryland Campaign. The V Corps attracted controversy during the battle when Fitz-John Porter failed to execute Pope's orders properly and attack Stonewall Jackson's flank despite his protests that James Longstreet's troops were blocking the way. Pope blamed the loss at Second Bull Run on Porter, who was court-martialed and spent much of his life attempting to get himself exonerated. Sigel's command, now redesignated the XI Corps, also spent the Maryland Campaign in Washington resting and refitting.
In the Maryland Campaign, the Army of the Potomac had six corps. These were the I Corps, commanded by Joe Hooker after Irvin McDowell was removed from command, the II Corps, commanded by Edwin Sumner, the V Corps, headed by Fitz-John Porter, the VI Corps, headed by William Franklin, the IX Corps, headed by Ambrose Burnside and formerly the Department of North Carolina, and the XII Corps, headed by Nathaniel Banks until September 12, and given to Joseph K. Mansfield just two days prior to Antietam, where he was killed in action.
At Antietam, the I and XII Corps were the first Union outfits to fight and both corps suffered enormous casualties (plus the loss of their commanders) so that they were down to near-division strength and their brigades at regimental strength after the battle was over. The II and IX Corps were also heavily engaged but the V and VI Corps largely stayed out of the battle.
When Burnside took over command of the army from McClellan in the fall, he formed the army into four Grand Divisions. The Right Grand Division was commanded by Edwin Sumner and comprised the II and XI Corps, the Center Grand Division, commanded by Joe Hooker, comprised the V and III Corps, and the Left Grand Division, commanded by William Franklin, comprised the VI and I Corps. In addition, the Reserve Grand Division, commanded by Franz Sigel, comprised the XI and XII Corps.
At Fredericksburg, the I Corps was commanded by John F. Reynolds, the II Corps by Darius Couch, the III Corps by George Stoneman, the V Corps by Daniel Butterfield, the VI Corps by William F. Smith, and the IX Corps by Orlando Willcox. The XI Corps was commanded by Franz Sigel and the XII Corps by Henry Slocum, however, neither corps was present at Fredericksburg, the former not arriving until after the battle was over, and the latter was stationed at Harper's Ferry.
Following Fredericksburg, Burnside was removed from command of the army and replaced by Joe Hooker. Hooker immediately abolished the Grand Divisions and also for the first time organized the cavalry into a proper corps led by George Stoneman instead of having them ineffectually scattered among infantry divisions. Burnside and his old IX Corps departed out to a command in the Western Theater. The I, II, and XII Corps retained the same commanders they had had during the Fredericksburg campaign, but the other corps got new commanders once again. Daniel Butterfield was chosen by Hooker as his new chief of staff and command of the V Corps went to George Meade. Daniel Sickles received command of the III Corps and Oliver Howard the XI Corps after Franz Sigel had resigned, refusing to serve under Hooker, his junior in rank. William Franklin also left the army for the same reason. Edwin Sumner, who was in his 60s and exhausted from campaigning, departed as well and died a few months later. William F. Smith resigned from command of the VI Corps, which was taken over by John Sedgwick. The I and V Corps were not significantly engaged during the Chancellorsville campaign.
During the Gettysburg Campaign, the army's existing organization was largely retained, but a number of brigades composed of short-term nine-month regiments departed as their enlistment terms expired. Darius Couch resigned from command of the II Corps after Chancellorsville, the corps going to Winfield Hancock. The Pennsylvania Reserves Division, having spent several months in Washington D.C. resting and refitting from the 1862 campaigns, returned to the army, but was added to the V Corps rather than rejoining the I Corps. George Stoneman had been removed from command of the cavalry corps by Hooker after a poor performance during the Chancellorsville campaign and replaced by Alfred Pleasanton.
George Meade was suddenly appointed the commander of the army on June 28, a mere three days before the battle of Gettysburg. At the battle, the I, II, and III Corps suffered such severe losses that they were almost nonfunctional as fighting units at the end. One corps commander (Reynolds) was killed, another (Sickles) lost a leg and was permanently out of the war, and a third (Hancock) was badly wounded and never completely recovered from his injuries. The VI Corps had not been significantly engaged and was mostly used to plug up holes in the line during the battle.
For the remainder of the war, corps were added and subtracted from the army. IV Corps was broken up after the Peninsula Campaign, with its headquarters and 2nd Division left behind in Yorktown, while its 1st Division moved north, attached to the VI Corps, in the Maryland Campaign. Those parts of the IV Corps that remained on the Peninsula were reassigned to the Department of Virginia and disbanded on October 1, 1863.Those added to the Army of the Potomac were IX Corps, XI Corps (Sigel's I Corps in the former Army of Virginia), XII Corps (Banks's II Corps from the Army of Virginia), added in 1862; and the Cavalry Corps, created in 1863. Eight of these corps (seven infantry, one cavalry) served in the army during 1863, but due to attrition and transfers, the army was reorganized in March 1864 with only four corps: II, V, VI, and Cavalry. Of the original eight, I and III Corps were disbanded due to heavy casualties and their units combined into other corps. The XI and XII Corps were ordered to the West in late 1863 to support the Chattanooga Campaign, and while there were combined into the XX Corps, never returning to the East.
The IX Corps returned to the army in 1864, after being assigned to the West in 1863 and then served alongside, but not as part of, the Army of the Potomac from March to May 24, 1864. On that latter date, IX Corps was formally added to the Army of the Potomac.Two divisions of the Cavalry Corps have transferred in August 1864 to Maj. Gen. Philip Sheridan's Army of the Shenandoah, and the 2nd Division alone remained under Meade's command. On March 26, 1865, that division was also assigned to Sheridan for the closing campaigns of the war.
†Major General John G. Parke took brief temporary command during Meade's absences on four occasions during this period)
Lt. Gen. Ulysses S. Grant, general-in-chief of all Union armies, located his headquarters with the Army of the Potomac and provided operational direction to Meade from May 1864 to April 1865, but Meade retained command of the Army of the Potomac.
Below is the grand recapitulation of the losses sustained by the Army of the Potomac and the Army of the James, from May 5, 1864 to April 9, 1865, compiled in the Adjutant-General's Office, Washington:
The Battle of Chancellorsville was a major battle of the American Civil War (1861–1865), and the principal engagement of the Chancellorsville campaign.
The Battle of Fredericksburg was fought December 11–15, 1862, in and around Fredericksburg, Virginia, in the Eastern Theater of the American Civil War. The combat, between the Union Army of the Potomac commanded by Maj. Gen. Ambrose Burnside and the Confederate Army of Northern Virginia under Gen. Robert E. Lee, included futile frontal attacks by the Union army on December 13 against entrenched Confederate defenders along the Sunken Wall on the heights behind the city. It is remembered as one of the most one-sided battles of the war, with Union casualties more than twice as heavy as those suffered by the Confederates. A visitor to the battlefield described the battle as a "butchery" to U.S. President Abraham Lincoln.
The Army of Northern Virginia was the primary military force of the Confederate States of America in the Eastern Theater of the American Civil War. It was also the primary command structure of the Department of Northern Virginia. It was most often arrayed against the Union Army of the Potomac.
The Battle of Antietam, or Battle of Sharpsburg particularly in the Southern United States, was a battle of the American Civil War fought on September 17, 1862, between Confederate Gen. Robert E. Lee's Army of Northern Virginia and Union Gen. George B. McClellan's Army of the Potomac near Sharpsburg, Maryland and Antietam Creek. Part of the Maryland Campaign, it was the first field army–level engagement in the Eastern Theater of the American Civil War to take place on Union soil. It remains the bloodiest day in American history, with a combined tally of 22,717 dead, wounded, or missing.
George Gordon Meade was a United States Army officer and civil engineer best known for decisively defeating Confederate General Robert E. Lee at the Battle of Gettysburg in the American Civil War. He previously fought with distinction in the Second Seminole War and the Mexican–American War. During the Civil War, he served as a Union general, rising from command of a brigade to that of the Army of the Potomac. Earlier in his career, he was an engineer and was involved in the coastal construction of several lighthouses.
Ambrose Everett Burnside was an American army officer who became a senior Union general in the Civil War and three times Governor of Rhode Island, as well as being a successful inventor and industrialist.
Joseph Hooker was an American Civil War general for the Union, chiefly remembered for his decisive defeat by Confederate General Robert E. Lee at the Battle of Chancellorsville in 1863.
The Peninsula campaign of the American Civil War was a major Union operation launched in southeastern Virginia from March through July 1862, the first large-scale offensive in the Eastern Theater. The operation, commanded by Maj. Gen. George B. McClellan, was an amphibious turning movement against the Confederate States Army in Northern Virginia, intended to capture the Confederate capital of Richmond. McClellan was initially successful against the equally cautious General Joseph E. Johnston, but the emergence of the more aggressive General Robert E. Lee turned the subsequent Seven Days Battles into a humiliating Union defeat.
John Fulton Reynolds was a career United States Army officer and a general in the American Civil War. One of the Union Army's most respected senior commanders, he played a key role in committing the Army of the Potomac to the Battle of Gettysburg and was killed at the start of the battle.
William Buel Franklin was a career United States Army officer and a Union Army general in the American Civil War. He rose to the rank of a corps commander in the Army of the Potomac, fighting in several notable battles in the Eastern Theater of the Civil War. He also distinguished himself as a civil engineer before and after the war.
The XI Corps was a corps of the Union Army during the American Civil War, best remembered for its involvement in the battles of Chancellorsville and Gettysburg in 1863.
The V Corps was a unit of the Union Army of the Potomac during the American Civil War.
I Corps was the designation of three different corps-sized units in the Union Army during the American Civil War. Separate formation called the I Corps served in the Army of the Ohio/Army of the Cumberland under Alexander M. McCook from September 29, 1862 to November 5, 1862, in the Army of the Mississippi under George W. Morgan from January 4, 1863 to January 12, 1863, and in the Army of the Potomac and Army of Virginia. The first two were units of very limited life; the third was one of the most distinguished and veteran corps in the entire Union Army, commanded by very distinguished officers. The term "First Corps" is also used to describe the First Veteran Corps from 1864 to 1866.
The Battle of Mine Run, also known as Payne's Farm, or New Hope Church, or the Mine Run campaign, was conducted in Orange County, Virginia, in the American Civil War.
The Bristoe campaign was a series of minor battles fought in Virginia during October and November 1863, in the American Civil War. Maj. Gen. George G. Meade, commanding the Union Army of the Potomac, began to maneuver in an unsuccessful attempt to defeat Gen. Robert E. Lee's Army of Northern Virginia. Lee countered with a turning movement, which caused Meade to withdraw his army back toward Centreville. Lee struck at Bristoe Station on October 14, but suffered losses in two brigades and withdrew. As Meade followed south once again, the Union army smashed a Confederate defensive bridgehead at Rappahannock Station on November 7 and drove Lee back across the Rapidan River. Along with the infantry battles, the cavalry forces of the armies fought at Auburn on October 13, again at Auburn on October 14, and at Buckland Mills on October 19.
The Maryland campaign occurred September 4–20, 1862, during the American Civil War. Confederate Gen. Robert E. Lee's first invasion of the North was repulsed by the Army of the Potomac under Maj. Gen. George B. McClellan, who moved to intercept Lee and his Army of Northern Virginia and eventually attacked it near Sharpsburg, Maryland. The resulting Battle of Antietam was the bloodiest single-day battle in American history.
The Eastern Theater of the American Civil War consisted of the major military and naval operations in the states of Virginia, West Virginia, Maryland, and Pennsylvania, the District of Columbia, and the coastal fortifications and seaports of North Carolina.
The Department of the Ohio was an administrative military district created by the United States War Department early in the American Civil War to administer the troops in the Northern states near the Ohio River.
The following Union Army units and commanders fought in the Battle of Antietam of the American Civil War. The Confederate order of battle is listed separately. Order of battle compiled from the army organization during the Maryland Campaign, the casualty returns and the reports.
The following Union Army units and commanders were the initial structure on April 4, 1862 of the Union Department of the Potomac during the Peninsula campaign of the American Civil War. This list includes units deployed to the Virginia Peninsula, and those that remained in the Washington area. The Confederate order of battle is listed separately.
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