You probably already have this info, but if you don't .................... He is also listed on several Federal Census records.

Widow's Confederate Pension
Name: W.E. Rosser
Spouse Name: Virginia Frances Rosser
Residence Location: Washington, Arkansas
Division: Cavalry
Regiment: Washington
Death Date: 14 May 1914
Comments: widow applied 1927 / questionnaire

@ Find-A-Grave
William Edward Rosser
BIRTH 7 Oct 1843
Campbell County, Virginia, USA
DEATH 14 Mar 1914 (aged 70)
BURIAL Evergreen Cemetery
Fayetteville, Washington County, Arkansas, USA
MEMORIAL ID 64420006