The Armies at Gettysburg > The Army of the Potomac
Organization of the 12th Corps of the Army of the Potomac in the Battle of Gettysburg.
The 12th Corps had 28 infantry regiments and 4 artillery batteries at Gettysburg, organized into two divisions of three brigades each and an artillery brigade.
12th Corps (monument)
Major General Henry Slocum (bio) (^ Right Wing) (monument)
Brigadier General Alpheus S. Williams
strength: 10,700 men, 20 guns
casualties: 205 killed, 810 wounded, 65 missing, 1,080 total
Provost Guard
10th Maine Infantry, Companies A, B & D (monument)
Captain John D. Beardsley
1st Division (monument)
Brigadier General Alpheus S. Williams (^ July 1)
Brigadier General Thomas H. Ruger
strength: 5,255 men
casualties: 95 killed, 405 wounded, 30 missing, 530 total
1st Brigade (monument)
Brigadier General Archibald L. McDougall
strength: 1,835 men
casualties: 12 killed, 60 wounded, 8 missing, 80 total
5th Connecticut Infantry Regiment (monument)
Colonel Warren W. Packer
20th Connecticut Infantry Regiment (monument)
Lieutenant Colonel William B. Wooster
3rd Maryland Infantry Regiment (monument)
Colonel Joseph M. Sudsburg
123rd New York Infantry Regiment (monument)
Lieutenant Colonel James C. Rogers
145th New York Infantry Regiment (monument)
Colonel E. Livingston Ptice
46th Pennsylvania Infantry Regiment (monument)
Colonel James L. Selfridge
2nd Brigade (monument)
Brigadier General Henry H. Lockwood
strength: 1,815 men
casualties: 35 killed, 120 wounded, 20 missing, 175 total
1st Maryland Regiment, Potomac Home Brigade (monument)
Colonel William P. Maulsby
1st Maryland Eastern Sore Infantry (monument)
Colonel James Wallace
150th New York Infantry Regiment (monument)
Colonel John H. Ketcham
3rd Brigade (monument)
Brigadier General Thomas H. Ruger
strength: 1,600 men
casualties:49 killed, 225 wounded, 5 missing, 279 total
27th Indiana Infantry Regiment (monument)
Colonel Silas Colgrove (^)
Lieutenant Colonel John R. Fesler
2nd Massachusetts Infantry Regiment (monument)
Lieutenant Colonel Charles R. Mudge (killed July 3)
Major Charles F. Morse
13th New Jersey Infantry Regiment (monument)
Colonel Ezra Carman
107th New York Infantry Regiment (monument)
Colonel Nirom M. Crane
3rd Wisconsin Infantry Regiment (monument)
Colonel William Hawley
2nd Division (monument)
Brigadier General John Geary (monument)
strength: 3,965 men
casualties: 110 killed, 395 wounded, 35 missing, 540 total
1st Brigade (monument)
Colonel Charles Candy
strength: 1,800 men
casualties: 18 killed, 119 wounded, 2 missing, 139 total
5th Ohio Infantry Regiment (monument)
Colonel John H. Patrick
7th Ohio Infantry Regiment (monument)
Colonel William R. Creighton
29th Ohio Infantry Regiment (monument)
Captain Wilber F. Stevens (wounded July 2 & 3)
Captain Edward Hayes
66th Ohio Infantry Regiment (monument)
Colonel Eugene Powell
28th Pennsylvania Infantry Regiment (monument)
Captain John Flynn
147th Pennsylvania Infantry Regiment (8 companies) (monument)
Lieutenant Colonel Ario Pardee
2nd Brigade (monument)
Colonel Ashworth Cobham, Jr. (*see note at bottom)
Brigadier General Thomas L. Kane
strength: 700 men
casualties: 23 killed, 66 wounded, 9 missing, 98 total
29th Pennsylvania Infantry Regiment (monument)
Colonel William Rickards, Jr.
109th Pennsylvania Infantry Regiment (monument)
Captain Frederick L. Gimber
111th Pennsylvania Infantry Regiment (monument)
Lieutenant Colonel Tomas M. Walker
Colonel Ashworth Cobham, Jr.
3rd Brigade (monument)
Brigadier General George Greene
strength: 1,425 men
casualties: 67 killed, 212 wounded, 24 missing, 303 total
60th New York Infantry Regiment (monument)
Colonel Abel Godard
78th New York Infantry Regiment (monument)
Lieutenant Colonel Herbert von Hammerstein
102nd New York Infantry Regiment (monument)
Colonel James C. Lane (wounded July 2)
Captain Lewis R. Stegman
137th New York Infantry Regiment (monument)
Colonel David Ireland
149th New York Infantry Regiment (monument)
Colonel Henry A. Barnum
Artillery Brigade (monument)
Lieutenant Edward D. Muhlenberg
strength: 400 men, 20 guns
casualties: 0 killed, 9 wounded, 0 missing, 9 total
1st New York Artillery, Battery M (monument)
Lieutenant Charles E. Winegar
4 10-pounder Parrott Rifles
Pennsylvania Independent Battery E (monument)
Lieutenant Charles A. Atwell
6 10-pounder Parrott Rifles
4th United States Artillery, Battery F (monument)
Lieutenant Sylvanus T. Rugg
6 Napoleons
5th United States Artillery, Battery K (monument)
1st Lieutenant David H. Kinzie
4 Napoleons
*note 1: Brigadier General Thomas Kane was in the hospital in Baltimore with pneumonia at the start of the Gettysburg campaign. He nevertheless rejoined the army and met up with his brigade by July 2. Too sick to take a fully active role, he was assisted by the senior colonel, Ashworth Cobham, Jr. of the 111th Pennsylvania.
*note 2: The 1st Division of the 12th corps went through several organization changes in May and June of 1863. After several regiments mustered out at the end of their terms the 1st and 2nd brigades were combined, leaving the division with no 2nd Brigade. A brigade made up of mostly Maryland home Guard troops took its place just prior to Gettysburg.
By this time 12th Corps commander Henry Slocum had been appointed temporary commander of the Army’s Right Wing, which temporarily bumped up 1st Division commander Alpheus Williams to 12th Corps commander. This would make the senior brigadier general the temporary 1st Division commander. By chance that would be the commander of the new brigade, Henry Lockwood, who had never been in combat and was an unknown quantity. The issue was resolved by making Lockwood’s Brigade independent, having it report directly to the corps commander. This left the experienced and capable Thomas Ruger in command of the division.
When the Right Wing idea was discarded during the battle Slocum returned to corps command, Williams to division command, and Lockwood’s Brigade could safely be made the 2nd Brigade of the division.