sentences:  He was always careful to avoid the title of "rex" – "king", and instead took on the titles of "princeps" – "first citizen" and "imperator", a title given by Roman troops to their victorious commanders.All these titles, alongside the name of "Caesar", were used by all Roman Emperors and still survive slightly changed to this date.Prince derives from "Princeps" and Emperor from "Imperator", Caesar became "Kaiser" (German) and "Czar" (Russian).