Overview
The 3rd Ohio Infantry (Three Months’ Service) was an infantry regiment organized at Camp Jackson, near Columbus, Ohio, in response to President Lincoln’s initial call for volunteers at the outbreak of the Civil War. The regiment entered Union service on April 27, 1861, for a term of three months. It served primarily in Ohio, focusing on organization, drill, and preparation for extended service. The unit was among the early regiments raised by Ohio and contributed to the rapid mobilization of Union forces in the Western Theater.
This unit is distinct from the 3rd Ohio Infantry (Three Years’ Service).
Organization & Service
The 3rd Ohio Infantry (Three Months’ Service) was organized at Camp Jackson on April 21, 1861, and mustered into Federal service on April 27, 1861. Shortly after mustering, a detachment was sent to Camp Dennison on April 28 to prepare a campsite, with the remainder of the regiment joining two days later. Throughout May 1861, the regiment was engaged in intensive drill and discipline at Camp Dennison, preparing for potential field service.
Before the regiment received orders for field deployment, the War Department called for volunteers to enlist for three years. The majority of the regiment reenlisted for the extended term, leading to the reorganization of the unit on June 12, 1861, and its subsequent muster into three years’ service on June 20, 1861. Members of the original three months’ organization who did not reenlist were mustered out on August 22, 1861. The regiment’s thorough training during its initial term enabled a smooth transition to active service under the new organization.
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
- Primarily engaged in organization, drill, and preparation for field service at Camp Dennison, Ohio (April–August 1861)
Casualties
Specific casualty figures for the 3rd Ohio Infantry (Three Months’ Service) are not reported in primary sources. The regiment did not participate in active combat during its three months’ term.
Field Officers & Commanders
- Colonel Isaac H. Marrow
- Lieutenant Colonel John Beatty
- Major J. Warren Keifer
Regimental Roster
The full roster of the 3rd Ohio Infantry (Three Months’ Service), including officers and enlisted men, is available for genealogical and historical research. This roster provides names, ranks, and service details for those who served during the regiment’s three months’ term.
To view the complete roster, visit the 3rd Ohio Infantry (Three Months’ Service) Roster page.
Sources & References
- Official Records of the Union and Confederate Armies, Series I, Vol. 2
- Ohio Roster Commission, “Official Roster of the Soldiers of the State of Ohio in the War of the Rebellion”
- Dyer, Frederick H., “A Compendium of the War of the Rebellion”
- Federal Publishing Company, “The Union Army,” Vol. 2