A fun story, Šćepan Mali took control of Montenegro and united the various tribes bu claiming to be Tsar Peter III of Russia.
While ruling from 1767 to 1773 he managed to reform the army and defeated the Ottomans (1768) and Venetians (1770). He received recognition from Russia after admitting he wasn't Peter and being named Tsar Šćepan I. He was assainated in 1773.
An assassination is fairly easy to butterfly away, but could someone who knows more about the situation and region weigh in on what the situation would be like if he survived?