I am also related to Henry Davis Allen. His father was Rhoda/Rhodam Allen. He was the first man buried in Jefferson Co., Ill. His wife was a Lucinda (?). He was born in Charles Co., Md in 1742 and died in Jefferson Co., Ill, Aug 24, 1820. He fought in the Revolutionary war and is a DAR patriot. I can give you more information if you would like. I have his father as Thomas Allen 1702-1770. Henry Davis Allen was a War of 1812 supplemental.