Overview
The 1st Pennsylvania Infantry (Three Months’ Service) was an infantry regiment organized at Harrisburg, Pennsylvania, for the Union Army at the outset of the Civil War. Composed of volunteers from Northampton, Dauphin, Lancaster, Berks, and Lehigh counties, the regiment was mustered into United States service between April 18 and 21, 1861, for a three months’ term. The unit served primarily in the Middle Department and the Shenandoah Valley during its brief period of service.
Organization & Service
The 1st Pennsylvania Infantry (Three Months’ Service) was organized at Harrisburg in response to President Lincoln’s initial call for troops. The regiment mustered in between April 18 and 21, 1861, under Colonel Samuel Yohe, Lieutenant Colonel Tilghman H. Good, and Major Thomas W. Lynn. Shortly after organization, the regiment departed Harrisburg on April 20 for Cockeysville, Maryland. However, concerns about provoking Maryland’s secession led to a withdrawal to the vicinity of York, Pennsylvania.
During early May 1861, the regiment performed guard duty along the Northern Central Railroad, ensuring the security of vital transportation lines. Later in May, it was assigned to guard the roads from Catonsville, Maryland, to Harper’s Ferry and Frederick, Maryland. On June 3, the regiment was ordered to Chambersburg and attached to General Robert Patterson’s army, then encamped at Funkstown, Maryland. The regiment spent approximately two weeks at Frederick, Maryland, followed by a week of garrison duty at Martinsburg, Virginia (now West Virginia). Subsequently, it was ordered to Charlestown and then to Harper’s Ferry. The regiment returned to Harrisburg on July 24, 1861, where it was mustered out of service at the expiration of its term.
Research This Regiment Further
If you’d like to explore this unit’s history in more depth, regimental histories and Civil War reference works offer valuable detail.
Engagements & Campaigns
- Guard duty along the Northern Central Railroad (May 1861)
- Guarding roads from Catonsville, MD, to Harper’s Ferry and Frederick, MD (late May 1861)
- Operations with General Patterson’s Army in Maryland and Virginia (June–July 1861)
- Garrison duty at Martinsburg, VA
- Duty at Charlestown and Harper’s Ferry
Casualties
Specific casualty figures for the 1st Pennsylvania Infantry (Three Months’ Service) are not detailed in primary sources. Available records indicate the regiment did not participate in major battles and suffered minimal losses during its term of service.
Field Officers & Commanders
- Colonel Samuel Yohe
- Lieutenant Colonel Tilghman H. Good
- Major Thomas W. Lynn
Regimental Roster
The complete roster of the 1st Pennsylvania Infantry (Three Months’ Service), including officers and enlisted men from Northampton, Dauphin, Lancaster, Berks, and Lehigh counties, is available for genealogical and historical research.
To view the full list of soldiers who served in this regiment, visit the 1st Pennsylvania Infantry (Three Months’ Service) Roster page.
Sources & References
- Official Records of the Union and Confederate Armies, Series I, Vol. 2
- Pennsylvania Adjutant General’s Report, 1861
- Dyer, Frederick H., A Compendium of the War of the Rebellion
- Federal Publishing Company, The Union Army, Vol. 1 (1908)