Here is a timeline for the Roman Republic and the Roman Empire.
The Roman Republic
The Roman republic emerged c. 509 BCE and declined between 133 and 31 BCE.
Coinage was developed with Caesar’s image:
The Roman Empire
Began with the Age of Augustus 31 BC – 14 AD. Augustus considered himself a princeps, meaning chief citizen, or first among equals.
He maintained a “standing army of twenty-eight legions. Since each legion at full strength numbered 5,400 soldiers, the Roman Empire had an army of about 150,000 men, certainly not large either by modern standards or in terms of the size of the empire itself (the population of the empire was probably close to 50 million)” (Spielvogel 150).
Canada has 65,000 in it’s standing army, and our population is about 32 million. 2/1000. So, per capita, the Romans had more.
The USA has 1,500,000, for a population of 300 million. 5/1000 per capita.
Under Augustus, the Praetorian Guard was set up. They were nine cohorts of elite troops, numbering about 9000 men. Their task was to guard the princeps. Eventually they were really important for making and deposing emperors.
One of his famous maxims was “make haste slowly,”(Speilvogel 153) which summarizes his efforts to establish the Roman Empire after his own image.
The early Roman empire overlaps with the beginning of Christianity, 14-180 AD.
It was a fractious period. Monty Python skit:
What have the Romans ever done for us?
Although the death of the historical figure Jesus of Nazareth coincided with this early period, Christianity did not come to dominate the Roman Empire until three centuries later, when Emperor Constantine converted. The 3rd Century was a century of Crisis for the Romans.
By the 4th Century, Christianity had become a major force in the Roman Empire.