I'm not sure if they where related, but my great great, great, great, grandfather was named Charles B Maxwell from Boston and served in the Civil war in the 1800s.  I believe he lived between 1833-1864.  One can read his original war diary here: http://www.blurb.com/books/2374573. I know I'm a direct descendant, as his diary has been passed down to us.  I'm not sure of the names to fill the gaps between Charles B. Maxwell and my grandfather. Perhaps there is something in his diary that may show a relationship to Robert Leland Maxwell.