Peninsula campaign order of battle: Union explained

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.^[1] The Confederate order of battle is listed separately.

Abbreviations used

Military rank

MG = Major General
BG = Brigadier General
Col = Colonel
Ltc = Lieutenant Colonel
Maj = Major
Cpt = Captain
Lt = Lieutenant

Army of the Potomac

See main article: Army of the Potomac. The following units were the initial organization of the Army of the Potomac on the peninsula.

MG George B. McClellan, Commanding

Headquarters and Body Guard

Co. A, 4th U.S. Cavalry: Lt James B. McIntire
Co. E, 4th U.S. Cavalry: Lt William O'Connell
Oneida Independent Cavalry Company: Cpt Daniel P. Mann
Sturges' Rifles: Cpt James Steele

Provost Guard

2nd U.S. Cavalry: Maj Alfred Pleasonton
Battalion of 8th U.S. Infantry (Cos. F & G) and 17th U.S. Infantry (Cos. B & D): Maj George L. Willard

Staff

Col Randolph B. Marcy, Chief of Staff
Maj Granville O. Haller, Commandant of General Headquarters

Function	Individuals
Adjutant BG Seth Williams	Ltc James A. Hardie (aide-de-camp) Cpt Richard B. Irwin
Inspector General Col Delos B. Sackett	Maj Nelson H. Davis
Engineers BG John G. Barnard	Ltc Barton S. Alexander Cpt Charles S. Stewart Lt Cyrus B. Comstock Lt Miles D. McAlester Lt William E. Merrill Lt Francis U. Farquhar
Topographical Engineers BG Andrew A. Humphreys	Lt Henry L. Abbot Lt Orlando G. Wagner Lt Nicholas Bowen Lt John Moulder Wilson
Medical Corps Charles S. Tripler	Surgeons and Nurses
Quartermaster Maj Stewart Van Vliet	Ltc Rufus Ingalls Ltc Charles G. Sawtelle
Commissary Col Henry F. Clarke	Col Amos Beckwith Ltc George Bell Ltc A. Parker Porter Cpt Thomas Wilson Cpt Brownell Granger Cpt William H. Bell Cpt John H. Woodward Cpt W.R. Murphy
Ordnance Cpt Charles P. Kingsbury	Lt Thomas G. Baylor Other unnamed officers
Provost-Marshal BG Andrew Porter	Maj William H. Wood Cpt James W. McMillan Cpt William T. Gentry Cpt James W. Forsyth Lt John W. Jones Lt Charles F. Trowbridge Lt Calvin D. Mehaffey
Judge Advocate Col Thomas T. Gantt	Unnamed officers
Signal Corps Maj Albert J. Myer	Unnamed officers
Telegraphic Office Maj Thomas Eckert	Mr. A. Harper Caldwell
Balloon Corps Professor Thaddeus S.C. Lowe	Lowe's Aeronauts
Personal Staff	Col Thomas M. Key Col Edward H. Wright Col John J. Astor, Jr.^[2] Ltc Albert V. Colburn Ltc Nelson B. Sweitzer Ltc Edward McK. Hudson Ltc Paul Von Radowitz Maj Herbert Von Hammerstein Maj William W. Russell (USMC) Maj Ferdinand Lecompte (Swiss Army Engineer) Cpt George A. Custer Cpt Joseph Kirkland Cpt Arthur McClellan Cpt Louis Philippe d'Orleans Cpt Robert d'Orleans Cpt Martin T. McMahon Cpt William P. Mason, Jr. Cpt William F. Biddle Cpt Edward A. Raymond

II Corps

See main article: II Corps (ACW). BG Edwin Sumner, Commanding
Ltc Joseph H. Taylor, Adjutant

width=25%	Division	width=25%	Brigade	Regiments and others
First Division BG Israel B. Richardson	First Brigade BG Oliver O. Howard	5th New Hampshire: Col Edward E. Cross 81st Pennsylvania: Col James Miller 61st New York: Col Francis C. Barlow 64th New York: Col Thomas J. Parker
	Second Brigade BG Thomas Francis Meagher	69th New York: Col Robert Nugent 63rd New York: Ltc John Burke 88th New York: Col Henry M. Baker
	Third Brigade BG William H. French	52nd New York: Col Paul Frank 57th New York: Col Samuel K. Zook 66th New York: Col Joseph C. Pinckney 53rd Pennsylvania: Col John R. Brooke
	Artillery	Batteries A & C, 4th U.S. Artillery: Cpt Francis N. Clarke Six Napoleons Battery G, 1st New York Artillery: Cpt John D. Frank Six 10-lb Parrotts Battery B, 1st New York Artillery: Cpt Rufus D. Pettit Six 10-lb Parrotts Battery A, 2nd New York Artillery:^[3] Cpt William H. Hogan Six 10-lb Parrotts
Second Division BG John Sedgwick	First Brigade BG Willis A. Gorman	2nd New York State Militia:^[4] Col George W.B. Tompkins 15th Massachusetts: Col Charles Devens
	Second Brigade BG William Wallace Burns	69th Pennsylvania: Col Joshua T. Owen 71st Pennsylvania: Col Isaac J. Wistar 72nd Pennsylvania: Col DeWitt Clinton Baxter 106th Pennsylvania: Col Turner G. Morehead
	Third Brigade BG Napoleon J.T. Dana	19th Massachusetts: Col Edward W. Hinks 20th Massachusetts: Col William R. Lee 7th Michigan: Col Ira R. Grosvenor 42nd New York: Col Edmund C. Charles
	Artillery	Battery I, 1st U.S. Artillery: Lt Edmund Kirby Six Napoleons Battery A, 1st Rhode Island Artillery: Cpt John A. Tompkins Four 10-lb Parrotts, two 12-lb howitzers Battery B, 1st Rhode Island Artillery: Cpt Walter O. Bartlett Four 10-lb Parrotts, two 12-lb howitzers Battery G, 1st Rhode Island Artillery: Cpt Charles Owen Six 3-inch ordnance guns
Cavalry reserve	Unbrigaded	8th Illinois Cavalry: Col John F. Farnsworth 6th New York Cavalry (Cos. D & K): Maj Floyd Clarkson

N.B. The Third Division under BG Louis Blenker was detached in early April and transferred to the Mountain Department

III Corps

See main article: III Corps (ACW). BG Samuel P. Heintzelman, Commanding
Cpt Chauncey McKeever, Chief of Staff

width=25%	Division	width=25%	Brigade	Regiments and others
First Division BG Fitz John Porter	First Brigade BG John H. Martindale	2nd Maine: Col Charles W. Roberts 18th Massachusetts: Col James Barnes 22nd Massachusetts: Col Jesse Gove 25th New York: Col Charles Johnson 13th New York: Col Elisha Marshall
	Second Brigade BG George W. Morell	14th New York: Col James McQuade 4th Michigan: Col Dwight A. Woodbury 9th Massachusetts: Col Thomas Cass 62nd Pennsylvania: Ltc Jacob B. Sweitzer
	Third Brigade BG Daniel Butterfield	17th New York: Col Henry S. Lansing 44th New York: Col Stephen W. Stryker 12th New York: Col Henry A. Weeks 83rd Pennsylvania: Col John W. McLane 16th Michigan: Col Thomas B. Stockton 1st Berdan Sharpshooters: Col Hiram Berdan
	Artillery Cpt Charles Griffin	Battery D, 5th U.S. Artillery: Cpt Charles Griffin Six 10-lb Parrotts Battery C, 1st Rhode Island Artillery: Cpt William B. Weeden Battery C, Massachusetts Artillery: Cpt Augustus C. Martin Six Napoleons Battery E, Massachusetts Artillery: Cpt George D. Allen Six 3-inch ordnance guns
Second Division BG Joseph Hooker	First Brigade BG Henry Morris Naglee	1st Massachusetts: Col Robert Cowdin 11th Massachusetts: Col William E. Blaisdell 26th Pennsylvania: Col William F. Small 2nd New Hampshire: Col Gilman Marston
	Second Brigade BG Daniel Sickles	70th New York: Col William Dwight 71st New York: Col George B. Hall 72nd New York: Col Nelson Taylor 73rd New York: Col William R. Brewster 74th New York: Col Charles K. Graham
	Third Brigade ("2nd New Jersey Brigade") Col Samuel H. Starr	5th New Jersey: Col William Joyce Sewell 6th New Jersey: Col James T. Hatfield 7th New Jersey: Col Joseph W. Revere 8th New Jersey: Col Adolphus J. Johnson
	Artillery Cpt Norman J. Hall	Battery H, 1st U.S. Artillery: Cpt Norman J. Hall Four 10-lb Parrotts, two 12-lb howitzers 4th New York Independent Battery: Cpt James E. Smith Six 10-lb Parrotts 6th New York Independent Battery: Cpt William M. Bramhall Six 3-inch ordnance guns Battery D, 1st New York Artillery: Cpt Thomas W. Osborn Four 3-inch ordnance guns
Third Division BG Charles Smith Hamilton	First Brigade Col Charles D. Jameson	105th Pennsylvania: Col Amor A. McKnight 63rd Pennsylvania: Col Alexander Hays 57th Pennsylvania: Col Charles T. Campbell 87th New York: Col Stephen Hodge
	Second Brigade BG David B. Birney	38th New York: Col J. H. Hobart Ward 40th New York: Col Edward J. Riley 3rd Maine: Col Moses B. Lakeman 4th Maine: Ltc Elijah Walker
	Third Brigade BG Hiram G. Berry	2nd Michigan: Col Orlando M. Poe 3rd Michigan: Col Stephen G. Champlin 5th Michigan: Col Henry D. Terry 37th New York: Col John H. McCunn
	Artillery Cpt James Thompson	Battery G, 2nd U.S. Artillery: Cpt James Thompson Six Napoleons Battery B, New Jersey Artillery: Cpt John E. Beam Four 10-lb Parrotts, two Napoleons Battery E, 1st Rhode Island Artillery: Cpt George E. Randolph Four 10-lb Parrotts, two Napoleons
Cavalry reserve	Unbrigaded	3rd Pennsylvania Cavalry: Col William W. Averell

Porter's Division was combined with Sykes' Division of the Reserve Corps and McCall's Division of the First Corps to form the Fifth Corps (Provisional) on May 18, 1862.

IV Corps

See main article: IV Corps (ACW). BG Erasmus D. Keyes, Commanding
Ltc Charles C. Suydam

width=25%	Division	width=25%	Brigade	Regiments and others
First Division BG Darius N. Couch	First Brigade Col Henry Shaw Briggs	2nd Rhode Island: Col Horatio Rogers, Jr. 7th Massachusetts: Col David Allen Russell 10th Massachusetts: Col Henry Shaw Briggs 36th New York: Col Charles H. Innes
	Second Brigade BG Lawrence P. Graham	67th New York: Col Julius W. Adams 65th New York: Col John Cochrane 23rd Pennsylvania: Col Thomas H. Neill 31st Pennsylvania: Col David H. Williams 61st Pennsylvania: Col Oliver H. Rippey
	Third Brigade BG John J. Peck	98th Pennsylvania: Col John F. Ballier 102nd Pennsylvania: Col Thomas A. Rowley 93rd Pennsylvania: Col James M. McCarter 62nd New York: Col John L. Riker 55th New York: Col P. Regis de Trobriand
	Artillery	Battery C, 1st Pennsylvania Artillery: Cpt Jeremiah McCarthy Four 10-lb Parrotts Battery D, 1st Pennsylvania Artillery: Cpt Edward H. Flood Four 10-lb Parrotts Battery E, 1st Pennsylvania Artillery: Cpt Theodore Miller Four Napoleons Battery H, 1st Pennsylvania Artillery: Cpt James Brady Four 10-lb Parrotts
Second Division BG W.F. "Baldy" Smith	First Brigade BG Winfield Scott Hancock	5th Wisconsin: Col Amasa Cobb 49th Pennsylvania: Col William H. Irwin 43rd New York: Col Francis L. Vinton 6th Maine: Col Hiram Burnham
	Second Brigade BG William T.H. Brooks	2nd Vermont: Col Henry H. Whiting 3rd Vermont: Ltc Breed N. Hyde 4th Vermont: Col Edwin H. Stoughton 5th Vermont: Col Henry A. Smalley 6th Vermont: Ltc Nathan S. Lord
	Third Brigade BG John Davidson	33rd New York: Col Robert F. Taylor 77th New York: Col James B. McKean 49th New York: Col Daniel D. Bidwell 7th Maine: Ltc Seldon Connor
	Artillery Cpt Romeyn B. Ayres	Battery F, 5th U.S. Artillery: Cpt Romeyn B. Ayres Four 10-lb Parrotts, two Napoleons 3rd New York Independent Battery: Cpt Thaddeus P. Mott Four 10-lb Parrotts, two Napoleons Battery E, 1st New York Artillery: Cpt Charles C. Wheeler Four 3-inch ordnance guns 1st New York Independent Battery: Cpt Terance J. Kennedy Six 3-inch ordnance guns
Third Division BG Silas Casey	First Brigade Col William W.H. Davis	104th Pennsylvania: Ltc John W. Neilds 52nd Pennsylvania: Col John C. Dodge 56th New York: Col Charles Van Wyck 100th New York: Col James M. Brown 11th Maine: Col John C. Caldwell
	Second Brigade BG William High Keim	85th Pennsylvania: Col Joshua B. Howell 101st Pennsylvania: Col Joseph H. Williams 103rd Pennsylvania: Col Theodore F. Lehmann 96th New York: Col James Fairman
	Third Brigade BG Innis N. Palmer	85th New York: Col Jonathan S. Belknap 98th New York: Col William Dutton 92nd New York: Col Jonah Sanford 81st New York: Col Edwin Rose 93rd New York: Col John S. Crocker
	Artillery Col Guilford D. Bailey	7th New York Independent Battery: Cpt Peter C. Regan Six 3-inch ordnance guns 8th New York Independent Battery: Cpt Butler Fitch Six 3-inch ordnance guns Battery A, 1st New York Artillery: Cpt Thomas H. Bates Six Napoleons Battery H, 1st New York Artillery: Cpt Joseph Spratt Four 3-inch ordnance guns
Cavalry Reserve	Unbrigaded	6th New York Cavalry (Cos. F & H): ?

W.F. Smith's Division was combined with Franklin's Division of the First Corps to form the Sixth Corps (Provisional) on May 18, 1862.

Reserves

width=25%	Division	width=25%	Brigade	Regiments and others
Cavalry BG Philip St. George Cooke	First Brigade BG William H. Emory	5th U.S. Cavalry: Cpt Charles J. Whiting 6th U.S. Cavalry: Maj Lawrence A. Williams 6th Pennsylvania Cavalry: Col Richard H. Rush
Cavalry BG Philip St. George Cooke	Second Brigade Col George A.H. Blake	1st U.S. Cavalry: Ltc William N. Grier 8th Pennsylvania Cavalry: Col David McM. Gregg Barker's Squadron, Illinois Cavalry: Cpt Charles W. Barker
Artillery Col Henry J. Hunt	Horse Artillery Brigade Ltc William Hays	Battery A, 2nd U.S. Artillery: Cpt John C. Tidball Six 3-inch ordnance rifles Batteries B & L, 2nd U.S. Artillery: Cpt James M. Robertson Six 3-inch ordnance rifles Battery M, 2nd U.S. Artillery: Cpt Henry Benson Six 3-inch ordnance rifles Batteries C & G, 3rd U.S. Artillery: Cpt Horatio G. Gibson Six 3-inch ordnance rifles
	Second Brigade Ltc George W. Getty	Battery K, 1st U.S. Artillery: Cpt William M. Graham Six Napoleons Batteries E & G, 1st U.S. Artillery: Lt Alanson M. Randol Six Napoleons Battery E, 2nd U.S. Artillery: Cpt J. Howard Carlisle Six 20-lb Parrotts Batteries L & M, 3rd U.S. Artillery: Cpt John Edwards, Jr. Six 10-lb Parrotts Batteries F & K, 3rd U.S. Artillery: Cpt La Rhett L. Livingston Four 10-lb Parrotts Battery G, 4th U.S. Artillery: Lt Charles H. Morgan Six Napoleons Battery K, 4th U.S. Artillery: Lt Francis W. Seeley Six Napoleons Battery I, 5th U.S. Artillery: Cpt Stephen H. Weed Six 3-inch ordnance guns Battery K, 5th U.S. Artillery: Cpt John R. Smead Four Napoleons Battery A, 5th U.S. Artillery: Cpt Adelbert Ames Four 10-lb Parrotts, two Napoleons
	Third Brigade Maj Albert Arndt	Battery A, 1st New York Artillery Battalion: Cpt Otto Diedrich Six 20-lb Parrotts Battery B, 1st New York Artillery Battalion: Cpt Adolph Voegele Four 20-lb Parrotts Battery C, 1st New York Artillery Battalion: Cpt John Knieriem Four 20-lb Parrotts Battery D, 1st New York Artillery Battalion: Cpt Edward Grimm Six 32-lb howitzers
Engineers	Volunteers BG Daniel Phineas Woodbury	15th New York: Col J. McLeod Murphy 50th New York: Col Charles B. Stuart
	Regulars Cpt James Chatham Duane	Co. A, U.S. Engineers: Lt Chauncey B. Reese Co. B, U.S. Engineers: Lt Charles E. Cross Co. C, U.S. Engineers: Lt Orville E. Babcock
	Artillery Siege Train	1st Connecticut Heavy Artillery: Col Robert O. Tyler
Infantry	Regulars BG George Sykes	2nd U.S. Infantry (9 companies): Ltc William Chapman 3rd U.S. Infantry (7 companies): ? 4th U.S. Infantry (10 companies): Ltc Robert C. Buchanan 6th U.S. Infantry (10 companies): Cpt Levi C. Bootes 10th & 17th U.S. Infantry (8 companies): ? 11th U.S. Infantry (6 companies): Cpt DeLancey Floyd-Jones 12th U.S. Infantry (8 companies): ? 14th U.S. Infantry (9 companies): ? 5th New York (Duryee's Zouaves): Col Gouverneur K. Warren

Sykes' Division was combined with Porter's Division of the Third Corps and McCall's Division of the First Corps to form the Fifth Corps (Provisional) on May 18, 1862.

Other Troops from the Department of the Potomac

The following troops were part of the Department of the Potomac in March and April 1861, but were detached to maintain defense of the Potomac River line.

I Corps

See main article: I Corps (Union Army). On April 4, the First Corps was renamed the Department of the Rappahannock, with authority to include the District of Columbia, Maryland between the Potomac and Patuxent, and Virginia between the Blue Ridge and the Fredericksburg & Richmond Railroad.

MG Irvin McDowell, Commanding
Ltc Edmund Schriver, Chief of Staff

Unattached cavalry

1st New York Cavalry: Col Andrew T. McReynolds
2nd New York Cavalry: Col J. Mansfield Davies
4th New York Cavalry: Col Christian F. Dickel

Sharpshooters

2nd Regiment, Berdan Sharpshooters: Col Henry A.V. Post

width=25%	Division	width=25%	Brigade	Regiments and others
First Division BG William B. Franklin	First Brigade BG Philip Kearny until Apr 30 BG Georg W. Taylor	1st New Jersey: Lt Col Robert McAllister 2nd New Jersey: Col Isaac M. Tucker 3rd New Jersey: Col George W. Taylor 4th New Jersey: Col James H. Simpson
	Second Brigade BG Henry Slocum	16th New York: Col Joseph Howland 27th New York: Col Joseph J. Bartlett 5th Maine: Col Clark S. Edwards 96th Pennsylvania: Col Henry L. Cake
	Third Brigade BG John Newton	18th New York: Col William H. Young 31st New York: Col Calvin E. Pratt 32nd New York: Col Roderick N. Matheson 95th Pennsylvania: Col John M. Gosline
	Artillery Cpt Edward R. Platt	Battery D, 2nd U.S. Artillery: Cpt Edward R. Platt Six Napoleons Battery A, Massachusetts Artillery: Cpt Josiah Porter Four 10-lb Parrotts, two 12-lb howitzers Battery A, New Jersey Artillery: Cpt William Hexamer Four 10-lb Parrotts, two 12-lb howitzers Battery F, 1st New York Artillery: Brady or Cpt William R. Wilson? Four 3-inch ordnance guns
Second Division (Pennsylvania Reserves) BG George A. McCall	First Brigade BG John F. Reynolds	1st Pennsylvania Reserves: Col R. Biddle Roberts 2nd Pennsylvania Reserves: Col William McCandless 5th Pennsylvania Reserves: Col Seneca G. Simmons 8th Pennsylvania Reserves: Col George S. Hays
	Second Brigade BG George Meade	3rd Pennsylvania Reserves: Col Horatio G. Sickel 4th Pennsylvania Reserves: Col Albert L. Magilton 7th Pennsylvania Reserves: Col Elisha B. Harvey 11th Pennsylvania Reserves: Col Thomas F. Gallagher
	Third Brigade BG Edward Ord	6th Pennsylvania Reserves: Col William Sinclair 9th Pennsylvania Reserves: Col Conrad F. Jackson 10th Pennsylvania Reserves: Col John S. McCalmont 12th Pennsylvania Reserves: Col John H. Taggart
	Skirmishers	1st Pennsylvania Reserve Rifles (Bucktails): Major Roy Stone
	Artillery Cpt Truman Seymour	Battery C, 5th U.S. Artillery: Cpt Truman Seymour Six Napoleons Battery A, 1st Pennsylvania Artillery: Cpt Hezekiah Easton Four Napoleons Battery B, 1st Pennsylvania Artillery: Cpt James H. Cooper Six 10-lb Parrotts Battery G, 1st Pennsylvania Artillery: Cpt Mark Kern Six 12-pounders
Third Division BG Rufus King	First Brigade BG Christopher C. Augur	84th New York (14th Brooklyn): Col Edward Brush Fowler 22nd New York: Col Walter Phelps 24th New York: Col Timothy Sullivan 30th New York: Col Edward Frisby
	Second Brigade BG Marsena R. Patrick^[5]	80th New York: Col George W. Pratt 21st New York: Col William F. Rogers 23rd New York: Col Henry C. Hoffman 35th New York: Col William C. Brown
	Third Brigade BG John Gibbon	2nd Wisconsin: Col Edgar O'Connor 6th Wisconsin: Col Lysander Cutler 7th Wisconsin: Col William W. Robinson 19th Indiana: Col Solomon Meredith
	Artillery	Battery B, 4th U.S. Artillery: Lt Joseph B. Campbell Six Napoleons Battery D, 1st Rhode Island Artillery: Cpt John A. Monroe Six 10-lb Parrotts Battery A, New Hampshire Artillery: Cpt George A. Gerrish Six Napoleons Durell's Independent Battery (D), Pennsylvania Artillery: Cpt George W. Durrell? Six 10-lb Parrotts

McCall's Division transferred to the Peninsula and was combined with Porter's Division of the Third Corps and Sykes' Division of the Reserve Corps to form the Fifth Corps (Provisional) on May 18, 1862. Franklin's Division transferred to the Peninsula and was combined with W.F. Smith's Division of the Fourth Corps to form the Sixth Corps (Provisional) on May 18, 1862.

V Corps

See main article: XII Corps (Union Army). On April 4, the Fifth Corps was renamed the Department of Shenandoah with authority over Maryland between the Blue Ridge and Flintstone Creek, Virginia between the Blue Ridge and the modern-day border with West Virginia.

MG Nathaniel P. Banks, Commanding
Cpt Louis H. Pelouze, Acting Assistant Adjutant General

Unattached Infantry

28th Pennsylvania: Col John W. Geary
4th Regiment Potomac Home Brigade (Maryland): ?

width=25%	Division	width=25%	Brigade	Regiments and others
First Division BG Alpheus S. Williams	First Brigade Col Dudley Donnelly	28th New York: Ltc Edwin F. Brown 5th Connecticut: Col George D. Chapman 46th Pennsylvania: Col Joseph F. Knipe 12th Indiana: ? 13th Massachusetts: Col Samuel H. Leonard
	Second Brigade BG John Joseph Abercrombie	12th Massachusetts: Col Fletcher Webster 2nd Massachusetts: Col George H. Gordon 16th Indiana: ? 1st Potomac Home Brigade (Maryland): Col William P. Maulsby Zouaves d'Afrique (one company): Cpt Charles H. T. Collis
	Third Brigade Col George Henry Gordon	83rd New York: Col John W. Stiles 29th Pennsylvania: Col John K. Murphy 27th Indiana: Col Silas Colgrove 3rd Wisconsin: Col Thomas H. Ruger
	Artillery Cpt Clermont L. Best	Battery F, 4th U.S. Artillery: Cpt Clermont L. Best Six Napoleons 1st Maryland Battery (Independent Battery F, Pennsylvania Artillery): Cpt Robert B. Hampton Four 10-lb Parrotts 2nd Maryland Battery (Independent Battery C, Pennsylvania Artillery): Cpt James Thompson Four 10-lb Parrotts Battery F, 1st Pennsylvania Artillery: Cpt Ezra W. Matthews Six 3-inch ordnance guns Battery M, 1st New York: Cpt George W. Cothran Six 10-lb Parrotts Independent Battery E, Pennsylvania Artillery: Cpt Joseph E. Knapp Six 10-lb Parrotts 15th Independent Battery, New York Artillery: Cpt Henry J. McMahon Six 3-inch ordnance guns
Second Division BG James Shields	First Brigade Col Nathan Kimball	14th Indiana: Ltc William Harrow 4th Ohio 8th Ohio: Col Samuel S. Carroll 67th Ohio: Col Alvin C. Voris? 7th Virginia: Col James Evans 84th Pennsylvania: Maj Walter Barrett
	Second Brigade Col Jeremiah C. Sullivan	5th Ohio: Col Samuel H. Dunning 62nd Ohio: Col Francis Bates Pond 66th Ohio: Col Charles Candy 13th Indiana: Ltc Robert S. Foster 39th Illinois: Col Thomas O. Osborn
	Third Brigade Col Erastus B. Tyler	7th Ohio: Ltc William R. Creighton 29th Ohio: Col Louis P. Buckley 7th Indiana: Col James Gavin 1st Virginia: Col Joseph Thoburn 110th Pennsylvania: Col William D. Lewis Andrew Sharpshooters: Cpt John Saunders
	Artillery Cpt Joseph C. Clark	Battery E, 4th U.S. Artillery: Cpt Joseph C. Clark Six 10-lb Parrotts Battery A, 1st Virginia Artillery: Cpt John Jenks Four 10-lb Parrotts, two Napoleons Battery B, 1st Virginia Artillery: Lt John V. Keeper Two 10-lb Parrotts Battery H, 1st Ohio Artillery: Cpt James F. Huntington Six 13-lb James Battery L, 1st Ohio Artillery: Cpt Frank C. Gibbs Two 12-lb howitzers, four Napoleons Battery, 4th Ohio Artillery^[6]
Cavalry	Unbrigaded	1st Maine Cavalry: Col Samuel H. Allen 1st Vermont Cavalry: Col Lemuel Platt 1st Michigan Cavalry: Col Thornton F. Brodhead 1st Pennsylvania Cavalry: Col George D. Bayard 1st Rhode Island Cavalry: Col Alfred N. Duffié 5th New York Cavalry: Col Othniel De Forest 8th New York Cavalry: Col Samuel J. Crook Keys' Battalion, Pennsylvania Cavalry: Lt Hugh Keys Eighteen companies, Maryland Cavalry: Col Henry A. Cole One company, Virginia Cavalry: Col Henry Anisansel

Shields' Division was transferred to the Department of the Rappahannock on May 10, 1862

District of Washington

BG James S. Wadsworth, Commanding

Regiments and others	Camp Location
1st New Jersey Cavalry	Alexandria City
4th Pennsylvania Cavalry Col James H. Childs	East of the Capitol
10th New Jersey Col William Bryan	Bladensburg Road
104th New York Col John Rohrbach	Kalorama Heights
1st Wisconsin Heavy Artillery ?	Fort Cass (Alexandria Co.)
New York Artillery (three batteries): ?	Fort Ethan Allen (Alexandria Co.) Fort Marcy (Fairfax Co.)
Depot of New York Light Artillery: ?	Camp Barry
2nd District of Columbia: Col Charles M. Alexander	Washington City
26th Pennsylvania: Col William F. Small	G Street Wharf
26th New York Col William H. Christian	Fort Lyon (present-day Huntington)
95th New York: Col George H. Biddle	Camp Thomas
94th New York: Col Henry K. Viele Detachment of 88th Pennsylvania: Maj George W. Gile	Alexandria City
91st Pennsylvania Col Edgar I. Gregory	Franklin Square Barracks (Franklin Square)
4th New York Heavy Artillery Col T.D. Doubleday	Fort Carroll (present-day Joint Base Anacostia-Bolling) Fort Greble (also present-day JBAB)
112th Pennsylvania: Col Charles Angeroth	Fort Saratoga
76th New York Ltc John D. Shaul	Fort Massachusetts (Washington Co.)
59th New York Col William L. Tidball	Fort Pennsylvania (Tenleytown)
Detachment of 88th Pennsylvania: ?	Fort Good Hope
99th Pennsylvania Col Peter Fritz	Fort Mahon
2nd New York Light Artillery: ?	Fort Ward (present-day Alexandria) Fort Worth (present-day Alexandria) Fort Blenker (present-day Fairlington)
107th Pennsylvania: Col Thomas A. Zeigel	Kendall Green (present-day Gallaudet University)
Dickenson's Light Artillery (16th Independent New York Battery) 86th New York: Col Benajah P. Baily Detachment of 88th Pennsylvania: Col George P. McLean	East of the Capitol
1st Massachusetts Heavy Artillery: Col Thomas R. Tannatt 56th Pennsylvania: Col Sullivan A. Meredith	Fort Albany Fort Tillinghast Fort Richardson Fort Runyon Fort Jackson Fort Barnard Fort Craig Fort Scott (all in present-day Arlington)
Detachment of 4th U.S. Artillery: ? 37th New York: Col John H. McCunn	Fort Washington (present-day Fort Washington, Maryland)
97th New York: Col Charles W. Wheelock 101st New York: Col Enrico Fardella ~~91st New York: Col Jacob Van Sandt~~^[7] 12th Virginia: Col John B. Klunk	Fort Corcoran (present-day Rosslyn)

Railroad Guards
Col Dixon S. Miles

6th New York Cavalry (Cos. A, B, C, E, G, I, K, & M dismounted): Col Thomas Devin
~~10th New York Cavalry (dismounted): Col John Lemmon~~^[8]
11th New York Cavalry (dismounted): Col James B. Swain
2nd Pennsylvania Cavalry (dismounted): Col Richard Butler Price

Troops Around Baltimore

On March 22, the Middle Department was created with authority over Pennsylvania, New Jersey, Delaware, and the Eastern Shore of Maryland and Virginia, as well as the Maryland counties of Cecil, Hartford, Baltimore, and Anne Arundel. Dix remained in command.

MG John A. Dix, Commanding
Maj Daniel Tompkins Van Buren, Chief of Staff and Acting Assistant Adjutant General

Type of Units	Regiments and others
Cavalry	1st Maryland Cavalry: Cpt Henry A. Cole? Purnell (Maryland) Legion Cavalry: Cpt Robert E. Duvall
Artillery	Battery I, 2nd U.S. Artillery: ? Battery A, Maryland Light Artillery: Cpt John W. Wolcott Battery L, 1st New York Artillery: Cpt John A. Reynolds Independent Battery ?, Pennsylvania Artillery: ? Independent Battery ?, Pennsylvania Artillery: ?
Infantry	3rd New York: Col Samuel M. Alford 4th New York: Col Alfred W. Taylor 11th Pennsylvania: Col Richard Coulter 87th Pennsylvania: Col George Hay 111th Pennsylvania: Col Matthew Schlaudecker Detachment, 21st Massachusetts: ? 2nd Delaware: Col W. Henry Wharton 2nd Maryland: Col John Sommer 1st Eastern Shore Home Guard (Maryland): Col James Wallace 2nd Eastern Shore Home Guard (Maryland): Col Robert S. Rogers Purnell (Maryland) Legion Infantry: Col Samuel L. Graham

Department of Virginia

The Department of Virginia constituted an area 60 miles from Fort Monroe. McClellan had received permission to absorb it into his army as a division of the First Corps, but it was rescinded shortly after he arrived on the Peninsula.

MG John E. Wool, Commanding

width=25%	Location	Regiments and others
Fort Monroe Maj Joseph Roberts	10th New York: Col John E. Bendix 99th New York (2 cos.): Maj Richard Nixon 7th Independent Battery, Massachusetts Artillery: Cpt Phineas Alonzo Davis Detachment, 4th U.S. Artillery: ? 2nd Independent Battery, Wisconsin Artillery: Cpt Ernst F. Herzberg 4th Independent Battery, Wisconsin Artillery: Cpt John F. Vallee
Camp Hamilton Col Max Weber	1st Delaware: Col John W. Andrews 16th Massachusetts: Col Powell T. Wyman 1st Michigan: Col John C. Robinson 20th New York: Ltc Francis Weiss 99th New York (6 cos.): Col David W. Wardop 58th Pennsylvania: Col John R. Jones Battery D, 4th U.S. Artillery: Cpt Frederick M. Follett 11th Pennsylvania Cavalry: Col Joseph Harlan 1st New York Mounted Rifles (4 cos.):^[9] Maj Charles C. Dodge
Camp Butler BG Joseph K. F. Mansfield	20th Indiana: Col William L. Brown 5th Maryland: Col William L. Schley 29th Massachusetts: Col Ebenezer W. Peirce 1st New York: Col Garrett Dyckman 2nd New York: Col Joseph B. Carr 7th New York: Col Edward Kapff 11th New York: Col Charles McK. Loeser Battery L, 4th U.S. Artillery: Cpt Robert V.W. Howard
Fort Wool Ltc Gustave B. Helleday	99th New York (2 cos.): Ltc Gustave B. Helleday

References

Troops of the Army of the Potomac sent to the Peninsula in March and early in April, 1862 The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies. United States War Department. Series I, Volume V, Chapter XXIV, pp. 19–32. (1881)
Additional Aides-de-Camp The New York Times. January 11, 1862.
Book: Carter . Robert Goldwaithe . Four Brothers in Blue: A Story of the Great Civil War from Bull Run to Appomattox . 1978 . 1913 . University of Texas Press . 0-8061-3185-3 .

Multiple commander names indicate command succession of command during the battle or the campaign.
The custom of the time was to attach the suffix "junior" to the younger living family member of the same name, not keep it consistent.
Later renamed 14th Independent Battery New York Artillery
In May the 90-day regiment would be mustered out and then mustered in as the 82nd New York, a three-year regiment
McClellan lists these units as being part of the New York State Militia, since all had previously served as ninety-days regiments with different numbers. But by March, they had all been mustered in as three-years regiments with these unit numbers.
No such battery is recorded outside of McClellan's official report. Ohio did not form a 4th Regiment of Artillery.
Listed by McClellan as present at the time of the Peninsula campaign, though it had already departed for Florida
Listed by McClellan as present at the time of the Peninsula campaign, though it was actually in Gettysburg at the time and would not join the Department of the Potomac until August.
Companies A, B, C, and D of the New York Mounted Rifles were all that had been recruited. Companies E and H were added in August, and Companies I through M were added in September.