Here’s what I have on the Pour le Mérite holder from page 557 of the source cited below:
April 9, 1918
Treusch von Buttlar-Brandenfels, Freiherr Horst
Kapitänleutnant, Commander, German Zeppelin L-54
Awarded the Pour le Mérite for outstanding leadership and distinguished military planning and successful zeppelin bombing operations. The award was also given in recognition of 15 flights over England including four bombing raids over London. On March 12, 1918, while over Grimsby, England, heavy antiaircraft fire caused the L-54 to lose an engine but Lt. Treusch von Buttlar-Brandenfels successfully brought the crippled airship back to Germany. He received a telegram advising and congratulating him on the award of the Pour le Mérite Order from Emperor Wilhelm II.
If you need more on him, I’d be more than happy to have a look in Douglas Robinson’s The Zeppelin in Combat: A History of the German Naval Airship Division, 1912-1918.
SOURCE: Hamelman, William E. The History of the Prussian Pour le Mérite Order, Volume III: 1888-1918. Matthäus Publishers, Dallas, Texas, 1986.