What led to the transformation of the Roman Republic into the Roman Empire ruled by one man?

The commencement of civil wars that took place between groups with different loyalties brought about the transformation of the republic into an empire. As groups started showing allegiance to different loyalties, it led to a civil war that transformed the Roman Republic to an Empire which was ruled by one man.

Explanation:

As power shifted from democracy,

Rome transitioned from a republic to an empire with a centralized imperial authority and the emperor holding the most power. In 45 BC - Julius Caesar became the first dictator of Rome. At this time, civil war broke out and Caesar became the supreme ruler of Rome. This brought the end of the Roman Republic.

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i dont have that book