Using Footnote.com, I found 14 pages in the Military Service record of John C and JC McWilliams of the 6th Louisiana Cavalry (Co C or E). The information indicated that he was born in Jefferson Cty, Alabama, lived in Bossier Parish on enlistment (farmer), was captured near New Orleans in May of 1865. He was also listed in the National Park service site (www.itd.nps.gov/cwss) as JC McWilliams of the 6th LA Cavalry. I have not checked 1860 census records.

Don Parker