8th Regiment, Missouri Cavalry (Union)
This regiment was organized at Springfield, Mo., August 6 to September 15, 1862. Attached to 2nd Brigade, 3rd Division, Army of the Frontier, Dept. of Missouri, to June, 1863. 1st Brigade, 1st Cavalry Division, District of Southeast Missouri, Dept. of Missouri, to August, 1863. 1st Brigade, 1st Cavalry Division, Arkansas Expedition, to December, 1863. 2nd Brigade, 1st Cavalry Division, Army of Arkansas, to January, 1864, and 7th Army Corps, Dept. of Arkansas, to May, 1864. 3rd Brigade, 2nd Division, 7th Army Corps, to September, 1864. 3rd Brigade, Cavalry Division, 7th Army Corps, to February, 1865. 2nd Brigade, Cavalry Division, 7th Army Corps, to March, 1865. 1st Separate Cavalry Brigade, 7th Army Corps, to July, 1865. 
For more information on the history of this unit, see:
- The Civil War Archive section, 8th Regiment Cavalry, (accessed 21 July 2012).
Another source says the 8th Regiment of the Missouri Cavalry (Union) enrolled between 20 July 1862 and 9 September 1862. They were Mustered between 30 July 1862 and 16 September 1862. They were discharged between 15 June 1865 and 20 July 1865. They were led by Colonel Washington T. Geiger.
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 - Captain William H. Kershmer - many men from Springfield, Missouri.
Company B - Captain Hamilton W. Goodyknootz - many men from Laclede County, Missouri.
Company C - Captain Albert Demuth - many men from Springfield, Missouri.
Company D - Captain Robert P. Matthews - many men from Springfield, Missouri.
Company E - Major William J. Bodenheimer, and Captains Luther J. Mathews, and Hugh Sheppard - many men from Springfield, Missouri.
Company F - Captains John B. Coffee, John M. Lacey, Levi P. McAdoo, and James M. Reaser - many men from Buffalo, Missouri.
Company G - Major James H. Carrison, and Captain Heorge Stepper - many men from Marshfield, Missouri.
Company H - Captains WIlliam Jones and Hugh Boyd - many men from Springfield, Missouri.
Company I - Captains Levi P. McAdoo and Nelson B. McDowell - many men from Springfield, Missouri.
Company K - Captains George Stepper, Edward D. Heathrington, and N. S. McCleur - many men from Polk County, Missouri.
Company L - Major Josephus G. Retch, and Captains Robert M. Keller, and Sanford H. Moore - many men from Marshfield, Missouri.
Company M - Captains Kennedy and Robert P. Mathews - many men from Springfield, 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 4.
- 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.