On page 142 of a book written by co authors: Robert J Driver,Jr and Kevin C Ruffner. Long title of their book is called "1st Battalion VA Infantry,39th Battalion VA Calvary,24th Battalion VA Partison Rangers" with IBN# 1-56190-093-1
under the 39th VA Calvary index,
following was printed: Johns,Joshua O: Pvt Co C reportedly WIA Chancellorsville 5/2/63 while serving as a Courier for Gen.Stonewall Jackson. Enl Orange CH 12/21/63. Present 10-12/64. Surrendered App Court House 4/9/65 with horse and equipment.

Of course, this only discussed the 39th VA Calvary.
Good Luck

Lee