121st Regiment, United States Colored Infantry
Organized at Maysville, Kentucky, October 8, 1864 - May 31, 1865.
It had garrison and guard duty at various points in Military District and Department of Kentucky until June, 1865.
It was discontinued June 30, 1865. 
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.
- Beginning United States Civil War Research gives steps for finding information about a Civil War soldier or sailor. It covers the major records that should be used. Additional records are described in 'Union Volunteers 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.
- Union Volunteers in the Civil War describes many Union sources, specifically for the Union Volunteers, 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 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.
- FamilySearch Wiki: Kentucky in the Civil War
- Kentucky's United States Colored Troops. By John R. Trowbridge: http://isaziz.tripod.com/ky_his.htm
- National Park Service, The Civil War Soldiers and Sailors System, (accessed 6 December 2010).
- Tabular Analysis of the Records of the U.S. Colored Troops and Their Predecessor Units in the National Archives of the United States. Special List No. 33. National Archives and records Service General Services Administration Washington: 1973.Compiled by Joseph B. Ross.FHL 973 M2rt Film:1036062 Item 21