Gettysburg Union order of battle

The following units and commanders fought in the Battle of Gettysburg of the American Civil War on the Union side. The Gettysburg Confederate order of battle is shown separately. When multiple names of commanders are shown, this indicates the succession of command through the three-day battle, (July 1–3, 1863). The number of men (and for artillery, guns) present at the battle are given in parenthesis.

Army of the Potomac

General Staff and Headquarters

MG* George G. Meade, Commanding.

General Staff and Headquarters
* Chief of Staff: MG Daniel Butterfield
* Chief of Artillery: BG Henry J. Hunt
* Assistant Adjutant General: BG Seth Williams
* Chief Quartermaster: BG Rufus Ingalls
* Medical Director: Dr Jonathan Letterman
* Chief Signal Officer: Capt Lemuel B. Norton
* Chief Ordnance Officer: Lt John R. Edie (acting)
* Bureau of Military Information: Col George H. Sharpe

* Provost Marshal General: BG Marsena R. Patrick (1,528)
** 93rd New York: Col John S. Crocker (148)
** 8th U.S. (8 companies): Capt Edwin W. H. Read (401)
** 2nd Pennsylvania Cavalry: Col R. Butler Price (489)
** 6th Pennsylvania Cavalry, Companies E and I: Capt James Starr (81)
** Regular cavalry (detachments from 1st, 2nd, 5th, and 6th Regiments) (15)
* Chief of Engineers: BG Gouverneur K. Warren
* Engineer Brigade: BG Henry W. Benham
** 15th New York (3 companies): Maj Walter L. Cassin
** 50th New York: Col William H. Pettes
** U.S. Battalion: Capt George H. Mendell
* Guards and Orderlies
** Oneida (New York) Cavalry: Capt Daniel P. Mann (42)

I Corps

* Total: 12,596 men
* I Corps Commanders:
** MG John F. Reynolds (k) Note: General Reynolds was commanding the "left wing" of the Army of the Potomac, with operational control over the I, III, and XI Corps, and Brig. Gen. John Buford's cavalry division.
** MG Abner Doubleday
** MG John Newton Note: John Newton replaced Abner Doubleday on the Second Day of Battle
* General HQ: 1st Maine Cavalry, Company L: Capt Constantine Taylor (57)

V Corps

* Total: 10,997
* V Corps Commander:
** MG George Sykes
* General HQ:
** 12th New York Infantry, Companies D and E: Capt Henry W. Rider (109)
** 7th Pennsylvania Cavalry, Companies D and H: Capt William Thompson (78)

XII Corps

* Total: 9,986
* XII Corps Commanders:
** MG Henry W. Slocum
** BG Alpheus S. Williams
* Provost Guard: 10th Maine (4 companies): Capt John D. Beardsley

* Military rank abbreviations used

* Gen = General
* LTG = Lieutenant General
* MG = Major General
* BG = Brigadier General
* Col = Colonel
* Ltc = Lieutenant Colonel
* Maj = Major
* Cpt = Captain
* Lt = Lieutenant
* Sgt = Sergeant

References

* Eicher, John H., [http://www.gdg.org/Research/OOB/EicherOOB.htm Gettysburg Order of Battle] at Gettysburg Discussion Group website.
* U.S. War Department, [http://cdl.library.cornell.edu/moa/browse.monographs/waro.html "The War of the Rebellion"] : "a Compilation of the Official Records of the Union and Confederate Armies"] , U.S. Government Printing Office, 1880–1901.