155th Pennsylvania Infantry in the American Civil War

Overview

The 155th Pennsylvania Infantry (Three Years’ Service) was an infantry regiment organized in Pennsylvania for service in the Union Army during the American Civil War. The regiment was composed primarily of eight companies from Allegheny County and two from Clarion County. It was mustered into United States service at Harrisburg and Pittsburgh during August and early September 1862 for a three-year term. The 155th served in the Eastern Theater, participating in many of the major campaigns of the Army of the Potomac.

The regiment was noted for its proficiency in French skirmish and bayonet drill and for its distinctive French Zouave uniforms. It played a significant role in several key battles, including Fredericksburg, Gettysburg, the Wilderness, Spotsylvania, and Petersburg, and was present at the surrender of Lee’s army at Appomattox.

Organization & Service

The 155th Pennsylvania Infantry was organized at Harrisburg and Pittsburgh, Pennsylvania, with the Allegheny County companies assembling at Camp Copeland near Pittsburgh and moving to Harrisburg on September 3, 1862. There, they were joined by Companies G and H from Clarion County, and the regiment was formally organized. Shortly after, the regiment departed for Washington, D.C., arriving just after the Second Battle of Bull Run. It was assigned to the 2nd Brigade, 3rd Division, 5th Corps, Army of the Potomac.

The regiment was held in reserve at Antietam but saw its first major action at Fredericksburg, suffering significant losses in the assault on Marye’s Heights. At Chancellorsville, the regiment was not heavily engaged. Following the mustering out of several nine-month regiments, the 155th was reassigned to the 3rd Brigade, 2nd Division, 5th Corps. At Gettysburg, it arrived on July 2, 1863, and was sent to defend Little Round Top, holding the position through the battle’s conclusion.

Throughout the fall of 1863, the regiment participated in the campaigns at Rappahannock Station and Mine Run, and was later posted along the Orange & Alexandria Railroad. Leadership changes occurred with the resignations of Colonels Allen and Cain, and Lieutenant Colonel Alfred L. Pearson was promoted to colonel. The regiment became known for its drill and appearance in Zouave uniforms.

In the spring of 1864, the 155th joined Ayres’ (1st) Brigade, Griffin’s (1st) Division, 5th Corps, and participated in the Overland Campaign, including the Wilderness, Spotsylvania, North Anna, Totopotomoy, Bethesda Church, and Cold Harbor. At Petersburg, it suffered heavy casualties in the assault of June 16, 1864. The regiment continued to serve in subsequent operations at Six Mile House, Peebles’ Farm, Hatcher’s Run, Weldon Railroad, and Dabney’s Mill.

During the final campaign of March–April 1865, the 155th distinguished itself at Quaker Road, Gravelly Run, Five Forks, and Sailor’s Creek. After the surrender at Appomattox, the regiment returned to Washington and was mustered out on June 2, 1865. The men were received with public honors in Pittsburgh before final discharge and payment.

Engagements & Campaigns

• Defenses of Washington, D.C. (September 1862)
• Battle of Fredericksburg (December 1862)
• Chancellorsville Campaign (May 1863)
• Battle of Gettysburg (July 2–3, 1863)
• Rappahannock Station (November 1863)
• Mine Run Campaign (November–December 1863)
• Overland Campaign: Wilderness, Spotsylvania Court House, North Anna, Totopotomoy, Bethesda Church, Cold Harbor (May–June 1864)
• Siege of Petersburg (June 1864–April 1865)
• Six Mile House (August 1864)
• Peebles’ Farm (September 1864)
• Hatcher’s Run (October 1864 and February 1865)
• Weldon Railroad Expedition (December 1864)
• Dabney’s Mill (February 1865)
• Appomattox Campaign: Quaker Road, Gravelly Run, Five Forks, Sailor’s Creek (March–April 1865)

Casualties

At Fredericksburg, the regiment lost 68 killed, wounded, and missing. At Chancellorsville, losses were 3 killed, 10 wounded, and 1 missing. At Gettysburg, 6 were killed and 13 wounded. In the Wilderness, 7 were killed, 42 wounded, and 6 missing. At Spotsylvania, 8 killed, 51 wounded, and 2 missing. At North Anna and Totopotomoy, 2 killed and 15 wounded. At Bethesda Church and Cold Harbor, 11 wounded and 1 missing. In the assault on Petersburg, June 16, 1864, 83 were killed and wounded in ten minutes. Additional losses occurred at Peebles’ Farm, Hatcher’s Run, Dabney’s Mill, and during the final campaign. Total regimental losses are not fully detailed in available primary sources.

Field Officers & Commanders

• Colonel Edward J. Allen
• Colonel John H. Cain
• Colonel Alfred L. Pearson (later brevet brigadier general and brevet major general)
• Lieutenant Colonel James Collard
• Lieutenant Colonel John H. Cain
• Lieutenant Colonel A. L. Pearson
• Lieutenant Colonel John Ewing
• Major John H. Cain
• Major A. L. Pearson
• Major John Ewing
• Major J. Andrew Cline

Regimental Roster

The full roster of the 155th Pennsylvania Infantry (Three Years’ Service), including officers and enlisted men, is available on the regiment’s roster page. This resource provides names, ranks, and additional service details valuable for genealogical and historical research.

To view the complete roster, visit the 155th Pennsylvania Infantry (Three Years’ Service) Roster page.

Sources & References

• Official Records of the Union and Confederate Armies, Series I, Volumes XIX, XXV, XXVII, XXXVI, XL, XLVI
• Pennsylvania Adjutant General’s Report
• Dyer, Frederick H., A Compendium of the War of the Rebellion
• Fox, William F., Regimental Losses in the American Civil War
• The Union Army, Federal Publishing Company, 1908, Volume 1