12th Regiment, Missouri Cavalry (Union)
This regiment was organized at St. Louis, Mo., November 3, 1863, to March 23, 1864. Attached to District of St. Louis, Mo., Dept. Missouri, to July, 1864. 1st Brigade, 1st Cavalry Division, District of West Tennessee, Dept. Tennessee, to November, 1864. 1st Brigade, 5th Division, Cavalry Corps. Military Division Mississippi, to May, 1865. Dept. Missouri, Eastern Division, Powder River Expedition, and District of the Plains to April, 1866. 
For more information on the history of this unit, see:
- The Civil War Archive section, 12th Regiment Cavalry, (accessed 21 July 2012).
Also see: 12th Regiment
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 - Major Andrew J. Jughes, Capatin Sidney Bennett - St. Louis, Missouri.
Company B - Caotaub Arthur J. Devlin and Captain Jhon W. Leach - St, Joseph, Buchanan, Missouri.
Company C - Campain William M. Delano and Captain William Coldwell - St. Joseph, Buchana Missouri.
Company D - Captain Joseph H. Rickards and Captain Charles F. Ernst - Carrolton, Carroll, Missouri.
Company E - Maptain Jefferson Miller - Breckenridge, Caldwell, Missouri.
Company F - Captain James K. Martin - Benton Barracks, St Lewis, Missouri
Company G - Captian William Kerrigan, Robert G. Hubbard and Sylvester S. VanSickle - Carrollton, Carroll, Missouri.
Company H - Major John Collar - Bethany, Harrison, Missouri.
Company I - Major William Mills, Captian John Caldwell and Captain William W. Taliafero - Waynswille, Pulaski, Missouri
Company K - Captian John G. Wood, Captain Robert B. McMillan and Captain William W. Owens - Tuscumbia, Miller, Missouri
Company L - Captian Henry T. Sherman and Captian Henary M. Serman - St Louis, Missouri.
Company M - Captian Oscar F. Smith - Memphis, Scotland, Missouri.
The above information about the companies with partial rosters is found in Kenneth E. Weant's book,(Civil War Records Union Troops Missouri Volunteer Calvary)Volume 5.
- 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 'Missouri 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.
- Missouri in the Civil War describes many Confederate and Union sources, specifically for Missouri, 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.