Very nice! A major with GGR Nr.4. Based on his rank and the Johanniter Order, he could be narrowed down to a few possibilities (unless the tunic is named, already). At a first cut, I would think he was either Maj. v. Pommer Esche (ultimately commander of JR85 and killed on 9/13/16) or Maj. v. der Hardt (ultimately commander of JR 408). There was also a Maj. Gr. zu Reventlow, but he died on 10/24/14, taking him off the list.