Williamson was present at roll calls until he was captured June 11, 1864 near Louisa Courthouse, Va. He was sent to Fortress Monroe, Va. on June 20th and on July 25th was transferred to Elmira Prison, N.Y.
Pvt. R.M. Williamson died December 31, 1864 at Elmira of pneumonia. He was buried in grave # 1331.