21st Regiment, Ohio Infantry (3 months, 1861)
The 21st Regiment, Ohio Infantry (3 months, 1861) mustered in April 27, 1861 at Camp Taylor, Cleveland, Tennessee. They were mustered out August 12, 1861. 
For more information on the history of this unit, see:
- The Civil War Archive section, 21st Regiment Infantry (3 months), (accessed 29 August 2012).
- Larry Stevens' Ohio in the Civil War, 21st Ohio Infantry
- Ohio Civil War Central, 21st Regiment Ohio Volunteer Infantry (Three Months), (accessed 7 November 2016).
Companies in this Regiment with the Counties of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first
Company A - Many men from Findlay, Hancock County
Company F - Many men from Findlay, Hancock County
The above information about the counties is from History of the 21st Regiment Ohio Volunteer Infantry in the War of the Rebellion, by S. S. Canfield, (Toledo, Ohio: Vrooman, Anderson and Bateman, 1893), p. 14. Internet Archive.
- 21st Ohio Regiment Infantry (3 months), Civil War Index, which includes history, battles, and roster with name, rank, age, date entered service, period of service and remarks.
- Beginning United States Civil War Research gives steps for finding information about a Civil War soldier. It covers the major records that should be used. Additional records are described in ‘Ohio in the Civil War’ and ‘United States Civil War, 1861 to 1865’ (see below).
- National Park Service, The Civil War Soldiers and Sailors System, is searchable by soldier's name and state. It contains basic facts about soldiers on both sides of the Civil War, a list of regiments, descriptions of significant battles, sources of the information, and suggestions for where to find additional information.
- Ohio in the Civil War describes many Confederate and Union sources, specifically for Ohio, and how to find them.. These include compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.
- United States Civil War, 1861 to 1865 describes and explains United States and Confederate States records, rather than state records, and how to find them. These include veterans’ censuses, compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.