Ossendowski joined the baron's army as a commanding officer of one of the self-defense troops. He also briefly became Ungern's political advisor and chief of intelligence. Little is known of his service at the latter post, which adds to Ossendowski's legend as a mysterious person. In late 1920, he was sent with a diplomatic mission to Japan and then the US, never to return to Mongolia. Some writers believe that Ossendowski was one of the people who hid the semimythical treasures of Baron Roman von Ungern-Sternberg.