with a
steeplechase race among the
Irish Brigade, drawn by
Edwin Forbes on March 17, 1863 Because of its proximity to the nation's largest cities at the time,
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, were well known to the general public, both during and after the Civil War.
Corps near
Petersburg, Virginia, photographed by
Matthew Brady in June 1864. Avery was killed on July 3, 1863, at the
Battle of Gettysburg. 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, which later became 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). Lincoln named as corps commanders the five highest-ranking division commanders in the army. McClellan was unhappy 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
First Battle of Kernstown in the Valley on March 23, the administration feared the threat to the national capital in
Washington, D.C. from
"Stonewall" Jackson's force. To McClellan's displeasure, it detached Blenker's division from the II Corps and sent it to
West Virginia, where it served under
John C. Fremont's command. McDowell's I Corps was detached as well and stationed in the Rappahannock area. In June 1862, George McCall's division from I 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, who was 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. In the battle, Pope issued confusing orders to the V Corps, eventually directing them against Jackson's flank, ignoring Longstreet's troops on the Union flank. Pope blamed the defeat at Second Bull Run on Porter, who was court-martialed and spent much of his life seeking exoneration. 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. ==Commanders==