Although I cannot name the parents of your John R Williams in question, you may want to look at the possibility of a Philip Williams born about 1780 who married a Miss Croudson. I know they had one son about 1800 named Samuel Croudston Williams. I suspect there were more children. Most of this information was compiled by studying cemetery information in the Manassas Cemetery and comparing with other Civil War Records on the name Williams. This information is only possibility to go on. Anne