He had a group of "secret police" called the Gestapo.
They bribed state and local officials in return for government appointments.
He was able to take complete power when it was thought that that wouldn't be possible.
Julius Ceasar was a trusted man.
The loosley connected city-states never united under one government, making them less powerful and less able to withstand invasion.
Julius Caesar was a man of many talents, interests and actions. He was able to gain cooperation from others by his personality and was able to charm the masses by that same personality. However, as far as ruling, he was too impatient to be a great ruler or even a good one.
Governments gain their just power through consent of the governed, typically through democratic elections or other forms of representation. Just power is also derived from upholding and protecting the rights and welfare of their citizens as outlined in laws and constitutions. Additionally, governments can gain legitimacy by establishing a fair and impartial system of justice.
The loosley connected city-states never united under one government, making them less powerful and less able to withstand invasion.
Stalin
That would be illegal and unconstitutional and upend the entirety of the American government.
Julius Caesar was an able Roman general.
If someone believes power corrupts, then they wouldn't be able to support any type of government fully. There is a balance of power no matter how casual the government.
He killed him. They were friends, but he had him killed. Stalin murdered millions.