Joachim's full name/title was Joachim Riedesel Freiherr (Baron) zu Eisenbach. One of his relatives is listed in a book on the Third Reich elite, receiving a posthumous promotion and being a recipient of the Knight's Grand Cross of the Iron Cross with Oak Leaves.
The ties continued into the modern day with another branch of the family--Marie Battenberg/Erbach's descendant (I think great-granddaughter), Countess Ulrike of Stolberg-Wernigerode (born 1940) married, as her second husband, Kurt-Joachim Riedesel, Baron zu Eisenbach in 1972. They have 2 children.
A Maria Franziska Riedesel zu Eisenbach (1717 - 1785) was an ancestress of Julie Hauke so there was a blood tie as well.