The First Corps of the Army of the Potomac was one of the four corps established by President Lincoln in March of 1862. He also appointed the corps commanders. This was over the objections of army commander George McClellan, who wanted to test the army in battle before creating corps and appointing corps commanders. Neither had ever been done before in an American army.

The First Corps never joined McClellan on the Peninsula, being held back by Lincoln to protect the road to Washington. It became the Department of the Rappahannock on April 4, 1862.

A new First Corps was created in September of 1862 from the Third Corps of John Pope’s Army of Virginia; none of the original First Corps were part of the new organization. It went on to lead the bloody morning attack at Antietam, saw action at Fredericksburg and Chancellorsville, and held the line as long as humanly possible on the first day of Gettysburg. Its survivors soldiered on until March of 1864, when it was discontinued in the big army reorganization, becoming part of the Fifth Corps. It’s memory was honored by allowing the men to continue to wear their First Corps symbols.

Flag of the First Division Red circle on White

Flag of the Second Division White circle on Blue

Flag of the Third Division Blue circle on White

Commanders of the First Corps:

Major General Irvin McDowell (March-April 1862)
Major General Joseph Hooker (September 12-17,1862)
Brigadier General George G. Meade (September 17-29, 1862)
Major General John Reynolds (September 1862-July 1863)
Major General Abner Doubeday (July 1-2, 1863)
Major General John Newton (July 1863-March 1864)

Month to month Order of Battle of the First Corps:

March 1862 April 1862

September 1862 October 1862 November 1862 December 1862

January 1863 February 1863 March 1863 April 1863

May 1863 June 1863 July 1863 August 1863

September 1863 October 1863 November 1863 December 1863

January 1864 February 1864 March 1864

Timeline of the First Corps, Army of the Potomac:

1862
March 3	The First Corps was created under the command of Major General Irvin McDowell. It included the divisions of William Franklin, George McCall and Rufus King
April 4	The First Corps was redesignated as the Department of the Rapahannock, becoming an independent command from McClellan’s Army of the Potomac.
September 12	The First Corps was recreated from the Third Corps of the Army of Virginia under the command of Major General Joseph Hooker. It consisted of the divisions of Rufus King, James Ricketts, and George Meade
September 14	Battle of South Mountain Rufus King gave up command of the First Division for medical reasons. He was briefly replaced by John Hatch, who was wounded. Abner Doubleday took over the First Division.
September 17	Battle of Antietam The First Corps opened the attack from the north toward the Dunker Church, fighting in the deadly Cornfield. General Hooker was wounded, and George Meade, commander of the Third Division, took command of the corps. Truman Seymour took over the Third Division from Meade. General Ricketts was badly injured but stayed on the field.
September 29	John Reynolds, who had commanded the Third Division while it was part of the Army of Virginia, was given command of the First Corps. Meade returned to command of the Third Division.
October 4	Ricketts was forced to give up command of the Second Division to Nelson Taylor due to his injury from Antietam.
November 5	Nelson Taylor was replaced by John Gibbon as commander of the Second Division
December 13	Battle of Fredericksburg John Gibbon was wounded, and Nelson Taylor resumed command of the Second Division.
December 25	George Meade took a leave of absence from the Third Division, leaving Horatio Sickle in command.
December 27-30	James Wadsworth replaced Abner Doubleday as commander of the First Division, and John Robinson replaced Nelson Taylor as Second Division commander.
1863
January 11	J. R. Kenly replaced Horatio Sickel as Third Division commander.
January 18	Abner Doubleday replaced J. R. Kenly as Third Division commander.
February	The Pennsylvania Reserves, who made up the Third Division, were transferred to the Washington Defenses to rest and recruit. A new Third Division of only two brigades was created in their place.
May	Battle of Chancellorsville The First Corps was only minimally engaged.
May 20	A brigade was dissolved in the Second Division as regiments mustered out at the end of their terms
June 13-16	Two brigades were dissolved in the First Division as regiments mustered out at the end of their terms
June 30	The Second Vermont Brigade was transferred from the Washington defences to the Third Division, but would not physically join the corps until reaching Gettysburg on July 1
July 1	Battle of Gettysburg – the First Day General Reynolds was killed early in the fighting and General Doubleday took over the corps. General Rowley took over the Third Division from Doubleday but was put under arrest and relieved at the end of the day.
July 2	Battle of Gettysburg – the Second Day Major General John Newton was transferred from division command in the Twelfth Corps to take over the corps, returning an angry Abner Doubleday to command of the Third Division.
July 7	General Doubleday, lightly wounded and with his requests to be returned to corps command denied, left the army. Brigadier J.R. Kenly took over the Third Division.
July 15	Brigadier General Wadsworth turned over the First Division to Brigadier General Lysander Cutler
August 5	Brigadier General H.S. Briggs took command of the First Division
August 23	Brigadier General J.C. Rice took took command of the First Division
September 23	Brigadier General Lysander Cutler took command of the First Division
1864
January 14	Brigadier General J.C. Rice took command of the First Division
February 10	Brigadier General Lysander Cutler returned to command of the First Division
March 20	Brigadier General J.C. Rice took command of the First Division
March 24	The First Corps was discontinued. General Newton was transferred to the Western Theater. The First Division and one brigade of the Third Division became the Fourth Division of the Fifth Corps, and the Second Division and the other brigade of the Third Division became the Second Division of the Fifth Corps. The men were allowed to continue to wear their First Corps badges.