Their first commander was Commander Andro Vrkljan, who was commissioned as a Fregattenkapitän (frigate captain) in the German navy.[1] Vrkljan was later replaced by Captain Stjepan Rumenović.[2] The Croats' purpose in posting a naval contingent to the Black Sea was to evade the prohibition on an Adriatic navy imposed by the Treaty of Rome (18 May 1941) with Italy.