Matt, do you know if it was for a Confederate or Union pension? Quick search revealed an Elisha Robertson in Company C 3rd Arkansas Calvary Union.
A Quick search at FamilySearch.com revealed an Elisha Roberston born about 1846 in Scott County Arkansas and died 1927. His parents listed as David Robertson (born Alabama around 1827) and Adeline Snell. David and Adeline were married 2 October 1843 in Shelby County Alabama.