How did Rome evolve from being governed by the people to being governed by an emperor?

Answer 1

The Roman Republic was torn apart by a series of bloody civil wars. The final civil war was a struggle between Octavian and Marc Antony over who would become the sole ruler of Rome and her territories. Octavian won and gained control over the Roman legions. He used this and the wealth he accumulated with the spoils of war to concentrate power in his hands. He established his personal rule and became the first Roman emperor. The senators who were opposed to this could not prevent Octavian from turning the (unelected) senate into an instrument for his power. The people supported him because he was the adoptive son of assassinated Julius Caesar who had been regarded as the hero of the people and because he restored peace after the destructiveness of the wars.

Historians use the name Augustus for the period when Octavian was an emperor. This was a title which was bestowed on him when he seized power. It can be translated as "The Exalted One" or "The Venerable One" and was a religious title. Thus, Augustus started the 503-year period of rule by emperors.