Nixon's Regiment, Tennessee Cavalry
Organized in spring of 1864; consolidated about March, 1865 with 14th (Neely's), 15th (Stewart's) and 21st (N.W. Carter's) to from Nixon's Consolidated Regiment; paroled at Gainesville, Alabama, May, 1865. 
"Units of the Confederate States Army" by Joseph H. Crute, Jr. contains no history for this unit.
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.
"This regiment was raised within enemy lines. The command so raised never received official designation by the Adjutant and Inspector Generals Office, but was known in the field as the 20th, the 22nd, or as Nixon's Regiment. No muster rolls, regimental returns, nor rosters of the regiment were found..."
- 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 'Tennessee 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.
- Tennessee in the Civil War describes many Confederate and Union sources, specifically for Tennessee, 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.
- Lindsley, John Berrien, The Military Annals of Tennessee – Confederate First Series, Embracing A Review of Military Operations, with Regimental Histories and Memorial Rolls, Compiled from Original and Official Sources, (Nashville: J.M. Lindsley & Co. Publishers; 1886).Online at Internet Archive, (accessed 3 Sep 2011). A brief history of the Twentieth Tennessee Cavalry (Nixon's) begins on page 738.
- Tennesseans in the Civil War, 22nd (Nixon's) Tennessee Cavalry Regiment, and Captain J.R. Williams' Tennessee Cavalry Company, (accessed 26 Apr 2012). A brief history.
- Other 20th Tennessee Cavalry Listings, (accessed 26 Apr 2012). This roster is developed from the microfilmed Compiled Service Records of Confederate Soldiers from Tennessee, microfilm series M268, roll 70, which is indexed as the 20th Tennessee Cavalry. This group contains record envelopes with prisoner and parole records showing service with the 20th Cavalry, but that the compilers did not connect to a specific unit (Russell's or Nixon's).