You probably already have this information, but will mention it just in case you do not.

William Preston of VA and his wife Caroline Hancock had a daughter named Henrietta Preston (some show her as Henerietta Johnston Preston) who married General Albert Sydney Johnston CSA (b. KY). They had a son, Col. William Preston Johnston. Some accounts say Gen. A. S. Johnston died in the arms of his father-in-law, Gen. William Preston at Shiloh; and that may be true, although it would be more correct to say ex-father-in-law since Henrietta had died and Johnston married secondly her cousin Eliza Croghan Griffin. The two women were cousins through their mothers in the Hancock family. William Preston Johnston later wrote a biography of famous father. (I did some research on this line hoping to connect, but alas, we are not related to this Johnston line, nor are we directly related to Gen.Joseph Eggleston Johnston. On the bright side, I found my own gg grandfather was a CSA Lt. Col. from MS and have since traced his line back thru KY and VA and didn't hit a brick wall until 1720 in Middlesex County.)