Complex sentence: The historian Robert Topmiller thought Ky may have seen the article as destabilizing and therefore decided to move against Thi, who was known to have the "deep-rooted" loyalty of his soldiers.
Split into simpler sentences: The historian Robert Topmiller thought that Ky may have seen the article as destabilizing and therefore decided to move against Thi. Thi was known to have the "deep-rooted" loyalty of his soldiers.