John Jamison [sic] enlisted as a Private in Company A, 20th Virginia Cavalry April 1, 1864 at Monongalia by Captain Camp for 3 years, last shown present on the August 31, 1864 muster, entitled to $50 bounty, records show payment on December 31, 1864, it appears this muster roll was taken at Liberty Mills & dated January 6, 1865, no further company muster rolls survived to be incorporated in these records

M324: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Virginia

20th Virginia Cavalry
Organized on August 14, 1863.
Disbanded on April 15, 1865.

Battles, Skirmishes and Engagements

Droop Mountain (November 6, 1863)
Lynchburg Campaign (June 1864)
Monocacy (July 9, 1864)
3rd Winchester (September 19, 1864)
Fisher's Hill (September 22, 1864)
Cedar Creek (October 19, 1864)

19th and 20th Virginia Cavalry, by Richard L. Armstrong, 1994. The 19th Virginia Cavalry included the Moccasin Rangers (A) from Calhoun and Wirt counties, The Braxton County Volunteers (B) from Braxton, Company C from Jackson and Roane counties, Company D from Marion County, Companies E, H, and K from Gilmer, the Pocahontas Cavalry (F) from Pocahontas, the Dixie Boys (G) from Kanawha, and Company I from Pocahontas and Randolph counties. The 20th Virginia Cavalry included Companies A and B from Marion and Monongalia counties, Company C from Randolph, Company D from Barbour, Companies E and F from Harrison, Company G from Wood and Pleasants, and Company H from Wirt.

19th and 20th Virginia Cavalry by Richard L. Armstrong

This book is part of the Virginia Regimental Histories Series, published by H. E. Howard, Inc

The 19thth Virginia Cavalry was created in the spring of 1863 from men who had served in the 3rd Virginia State Line (disbanded in 1863). Colonel William L. Jackson was assigned to command the regiment. Colonel Jackson was a cousin of "Stonewall" Jackson, and was called "Mudwall" and "Brickwall." Most of the men in this regiment lived in Northwestern Virginia.

The 20th Virginia Cavalry was formed in the fall of 1863 and was commanded by Colonel W. W. Arnett. Both of these regiments served under Colonel Jackson as part of Jackson's Brigade, until the close of the war.

The book contains a textual history of the regiment from its organization until the close of the war. There are photographs of the veterans of the regiment. A roster of all the known (or suspected) members of the regiment is included.
http://history-sites.com/books.htm