| Unit Name: | 12th New Hampshire Infantry Regiment |
| Dates: | September 10, 1862, to June 21, 1865 |
| Country: | United States |
| Allegiance: | Union |
| Branch: | Infantry |
| Size: | 1,450 |
| Battles: |
The 12th New Hampshire Infantry Regiment was an infantry regiment that served in the Union Army during the American Civil War. It was also a unit that existed for a time following the Revolutionary War (see the History of Fitzwilliam, NH (Norton), p. 351-353).
The 12th New Hampshire Infantry was organized in Concord, New Hampshire, and mustered in for a three-year enlistment on September 10, 1862, under the command of Colonel Joseph Haydn Potter.
The regiment was attached to Casey's Division, Military District of Washington, to December 1862. 2nd Brigade, 3rd Division, III Corps, Army of the Potomac, to June 1863. 1st Brigade, 2nd Division, III Corps, Army of the Potomac, to July 1863. Marston's Command, Point Lookout, Maryland, District of St. Mary's, to April 1864. 2nd Brigade, 2nd Division, XVIII Corps, Department of Virginia and North Carolina, to December 1864. 2nd Brigade, 3rd Division, XXIV Corps, Department of Virginia, to June 1865.
The 12th New Hampshire Infantry mustered out of service June 21, 1865.
| Dates | Actions/Events | |
|---|---|---|
| 1862 | ||
| September 27 | Left New Hampshire for Washington, D.C. | |
| Until October | Duty in the defenses of Washington | |
| October 18 | Moved to Point of Rocks, Md. | |
| October 19 | Then moved to Pleasant Valley | |
| October 24-November 16 | Moved to Warrenton, Va. | |
| November 18–24 | Moved to Falmouth | |
| December 12–15 | Battle of Fredericksburg | |
| 1863 | ||
| January 20–24 | Burnside's 2nd Campaign ("Mud March") | |
| Until April | Duty at Falmouth | |
| April 27-May 6 | Chancellorsville Campaign | |
| May 1–5 | Battle of Chancellorsville | |
| June 11-July 24 | Gettysburg Campaign | |
| July 1–3 | Battle of Gettysburg | |
| July 26 | Ordered to Point Lookout, Md. with duty there guarding prisoners until April 7, 1864. | |
| 1864 | ||
| April 7 | Moved to Yorktown then to Williamsburg | |
| May 4–28 | Butler's operations on south side of the James River and against Petersburg and Richmond | |
| May 9–10 | Swift Creek (or Arrowfield Church) | |
| May 12–16 | Operations against Fort Darling | |
| May 14–16 | Battle of Drewry's Bluff | |
| May 16–27 | Bermuda Hundred | |
| May 27–31 | Moved to White House, then to Cold Harbor | |
| June 1–12 | Battles about Cold Harbor | |
| June 15–19 | Before Petersburg | |
| June 16 to April 2, 1865 | Siege of Petersburg and Richmond | |
| July 30, 1864 | Mine Explosion, Petersburg (Reserve) | |
| August 26 to December | Duty on the Bermuda Front | |
| 1865 | ||
| April 1865 | In trenches before Richmond | |
| April 3 | Occupation of Richmond | |
| Until June | Guard and provost duty at Manchester | |
On July 2, 1863, the 12th New Hampshire was heavily engaged north of the Klingel Farm, facing attack by Wilcox's Alabama brigade. The regiment had 224 men on the field that day, of whom 26 were killed and 73 were wounded (an additional six men would die of their wounds). Captain John F. Langley (Company F) was in command, and was wounded when the regiment was ordered to withdraw. Lieutenant William H. H. Fernel (Company I) took command and was able to rescue some 50 Union soldiers who were captured during the withdrawal. The following day, only 50 men were fit for duty under the command of Captain Thomas E. Barker (Company B). Placed near the center of the Union line, they helped repulse Pickett's charge.
The regiment lost a total of 320 men during service; 11 officers and 170 enlisted men killed or mortally wounded, 1 officer and 138 enlisted men died of disease.