Carol, This William was the son of John Mattingly (son of John son of Cezar). I have no source for the name of his mother, other than Elizabeth. I have not seen any source that she was a Brewer (not to say that she isn't but William's grandparents were John and Grace Mattingly and perhaps the source is getting their signals crossed since Grace was suspected to be a Brewer). William is listed in the administrative accounts of his father, John, and is listed as being born in 1747. We probably have more info on this William but I suspect that we have it attributed to the many different Williams in MD (William of Thomas II and William of Ignatius of Thomas II). If you check your source and find out anything else, let us know. I would love to learn more about the children of John. Paul