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.

After the Second Battle of Bull Run, the Army of the Potomac absorbed the units that had served under Maj. Gen. John Pope.

The belief that John Pope commanded the Army of the Potomac in the summer of 1862 after McClellan's unsuccessful Peninsula Campaign is mistaken.

However, the name was eventually changed to the Army of Northern Virginia, which became famous under General Robert E. Lee.

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.

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 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.

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.

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 addition, the Reserve Grand Division, commanded by Franz Sigel, comprised the XI and XII Corps.

Daniel Butterfield was chosen by Hooker as his new chief of staff and command of the V Corps went to George Meade.

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.

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.

††Major General John G. Parke took brief temporary command during Meade's absences on four occasions during this period) Notes Bibliography Further reading