20th Massachusetts Infantry Regiment

20th Massachusetts Infantry Regiment
source
Unit name	20th Massachusetts Infantry Regiment
Dates	August 1861 – August 1864
Country	United States
Allegiance	Union
Branch	Infantry
Type	Regiment
Size	Regiment
Command structure	Army of the Potomac
Garrison	Boston, Massachusetts
Battles	American Civil War, Battle of Ball's Bluff, Siege of Yorktown (1862), Battle of Antietam, Battle of Fredericksburg, Battle of Chancellorsville, Battle of Gettysburg, Overland Campaign

20th Massachusetts Infantry Regiment The 20th Massachusetts Infantry Regiment was a three-year volunteer infantry regiment raised in Massachusetts for service in the American Civil War. Organized in Boston, Massachusetts in August 1861, the regiment served in multiple major campaigns with the Army of the Potomac and saw action in key battles across Virginia, Maryland, and Pennsylvania before mustering out in August 1864. Its service connected it to prominent formations and commanders of the conflict, including associations with corps and divisions engaged at Antietam, Gettysburg, and the Overland Campaign.

Formation and Organization

The regiment was mustered at Boston, Massachusetts under state authorization following calls from President Abraham Lincoln and state authorities in 1861, drawing volunteers from Suffolk County, Massachusetts, Middlesex County, Massachusetts, Worcester County, Massachusetts, and Essex County, Massachusetts. Its companies were designated A through K and organized under the initial command of Colonel Thomas Cass, reflecting recruitment influences from municipal leaders in Salem, Massachusetts, Worcester, Massachusetts, and neighborhoods of Boston, Massachusetts. The unit was assigned to brigades within the II Corps and later brigades of the V Corps and attached to divisions operating under generals such as George B. McClellan, Joseph Hooker, and George G. Meade.

Service History

After training in Camp Meigs and embarkation from Boston Harbor, the regiment moved to the vicinity of Washington, D.C. to join the defenses of the capital and the field armies assembling for the Peninsula Campaign. It participated in the opening operations of the Army of the Potomac under George B. McClellan and moved into the campaign against Richmond, Virginia. The 20th Massachusetts took part in the withdrawal to the north during the Maryland Campaign and fought at Antietam before wintering with the army. In 1863 the regiment fought in the Chancellorsville Campaign and was heavily engaged at Gettysburg, after which it was involved in pursuit operations and defensive duties along the Rappahannock River. During 1864 the regiment joined the Overland Campaign under Ulysses S. Grant and took part in assaults during the push toward Richmond, Virginia and Petersburg, Virginia until veterans and recruits were transferred and the regiment mustered out in August 1864.

Engagements and Campaigns

The 20th Massachusetts saw combat in multiple named engagements and sustained operations: - Battle of Ball's Bluff (early service actions in the Eastern Theater). - Peninsula Campaign and the Siege of Yorktown (1862) during operations before Richmond, Virginia. - Maryland Campaign including the Battle of Antietam along the Potomac River. - Battle of Fredericksburg operations during the winter campaigns. - Chancellorsville Campaign including the Battle of Chancellorsville. - Gettysburg Campaign culminating at Battle of Gettysburg in Pennsylvania. - Pursuit operations after Gettysburg and winter campaigns in 1863–1864 along the Rappahannock River and Rappahannock Campaigns. - Overland Campaign engagements advancing toward Richmond, Virginia and Petersburg, Virginia under Ulysses S. Grant.

Commanders and Notable Members

Leadership and notable soldiers included Colonel Thomas Cass as the regiment’s first colonel, with subsequent leadership including Lieutenant Colonel James Barnes and field officers who served in brigade and division staff roles. Company officers and enlisted men from locales such as Boston, Massachusetts, Worcester, Massachusetts, Salem, Massachusetts, and Lowell, Massachusetts went on to serve in state militia and civic posts after the war. Members who achieved later prominence or recognition participated in veteran organizations such as the Grand Army of the Republic and contributed to regimental histories compiled in Massachusetts archives and veterans’ memoirs.

Casualties and Strength

Muster rolls for the 20th Massachusetts indicate an initial authorized strength typical of three-year regiments formed in 1861, with total enrollment across muster, reenlistment, and recruits numbering in the hundreds. The regiment sustained casualties from combat at battles including Antietam, Fredericksburg, Chancellorsville, and Gettysburg, as well as losses from disease during encampments near Washington, D.C. and southern camps. Officers and enlisted men were killed, wounded, captured, and mortally wounded, with many soldiers recorded on casualty lists maintained in National Archives collections and state adjutant general reports.

Legacy and Commemoration

The 20th Massachusetts is commemorated in regimental monuments and markers at battlefields such as Antietam National Battlefield and Gettysburg National Military Park, and in Massachusetts memorials erected by veterans’ groups and municipal historical societies in Boston, Massachusetts and Worcester, Massachusetts. Regimental histories, soldier letters, and rosters are preserved in repositories including the Massachusetts Historical Society, Library of Congress, and state archives, contributing to scholarship on the Army of the Potomac and volunteer regiments of the American Civil War. Annual commemorations by descendants and reenactment organizations recall the regiment’s service in the defining campaigns of the war.

Category:Units and formations of the Union Army from Massachusetts Category:Military units and formations established in 1861 Category:Military units and formations disestablished in 1864