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.Multiple commander names indicate command succession of command during the battle or the campaign. 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
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 Lt James H. Wilson Medical Corps
Charles S. TriplerSurgeons 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.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. 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
BG Edwin Sumner, Commanding Ltc Joseph H. Taylor, Adjutant
Division Brigade Regiments and othersFirst 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:Later renamed 14th Independent Battery New York Artillery Cpt William H. Hogan Six 10-lb ParrottsSecond Division
BG John Sedgwick First Brigade
BG Willis A. Gorman 2nd New York State Militia:In May the 90-day regiment would be mustered out and then mustered in as the 82nd New York, a three-year regiment Col George W.B. Tompkins 15th Massachusetts: Col Charles Devens 1st Minnesota: Col Alfred Sully 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 gunsCavalry 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
BG Samuel P. Heintzelman, Commanding Cpt Chauncey McKeever, Chief of Staff
Division Brigade Regiments and othersFirst 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 gunsSecond 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 gunsThird 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 NapoleonsCavalry 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
BG Erasmus D. Keyes, Commanding Ltc Charles C. Suydam
Division Brigade Regiments and othersFirst 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 ParrottsSecond 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 gunsThird 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