1st Massachusetts Infantry Regiment

1st Regiment Massachusetts Volunteer Infantry
"Charge of the First Massachusetts Regiment on a Rebel Rifle Pit near Yorktown," by Winslow Homer, 1862
Active	May 23, 1861–May 25, 1864
Country	United States of America
Branch	Union Army
Type	Infantry
Part of	In 1863: 1st Brigade (Carr's), 2nd Division (Humphreys's), III Corps, Army of the Potomac
Battle honours	Battle of Blackburn's Ford First Battle of Bull Run Siege of Yorktown Battle of Williamsburg Battle of Seven Pines Battle of Glendale Second Battle of Bull Run Battle of Fredericksburg Battle of Chancellorsville Battle of Gettysburg Battle of Mine Run Battle of the Wilderness Battle of Spotsylvania Court House
Commanders
Notable commanders	Col. Robert Cowdin Col. Napoleon B. McLaughlen
Insignia
III Corps (2nd Division) badge

The 1st Regiment Massachusetts Volunteer Infantry was an infantry regiment in the Union army during the American Civil War. It was the first regiment to leave Massachusetts for a three-year term (several had previously left for 90-day terms) in response to President Abraham Lincoln's May 3, 1861, call for three-year regiments.^[1] It was also the first three-year regiment from any state to reach Washington, D.C., for federal service.^[2] The core of the regiment was five companies from the 1st Massachusetts Volunteer Militia, a peace-time unit which was formed in 1858, replacing an earlier, disbanded unit of the same designation. Five companies of new recruits were added to the regiment and the unit was mustered in by companies beginning May 23, 1861, at Camp Cameron in Cambridge, Massachusetts.

After arriving in Washington, the regiment became part of Major General Irwin McDowell's Army of Northeastern Virginia and saw their first combat during the Battle of Blackburn's Ford. The 1st Massachusetts was engaged during the First Battle of Bull Run. When Union forces surrounding Washington were reorganized, the regiment became part of the Army of the Potomac, with which it was associated for the rest of its term of service. It was involved in the Peninsular Campaign and was present for virtually all of the major battles in which the Army of the Potomac fought, including the Second Battle of Bull Run, the Battle of Fredericksburg, the Battle of Chancellorsville, the Battle of Gettysburg and Lieutenant General Ulysses Grant's Overland Campaign.