What happened 27 AD

The Red Eyebrows surrendered to the Han dynasty.

The constitutional history ended with constitutional reforms that transformed the Republic into what would effectively be the Roman Empire, in 27 BC.

Caesar Augustus, also known as Octavian, was the first Roman emperor, reigning from 27 BC until his death in AD 14. His status as the founder of the Roman Principate (the first phase of the Roman Empire) has consolidated a legacy as one of the most effective leaders in human history.

On 16 January 27 BC the Senate gave Octavian the new titles of Augustus and Princeps. Augustus is from the Latin word Augere (meaning to increase) and can be translated as "the illustrious one". It was a title of religious authority rather than political authority. His new title of Augustus was also more favorable than Romulus, the previous one which he styled for himself in reference to the story of the legendary founder of Rome, which symbolized a second founding of Rome.

In January 27 BC Octavian was renamed Augustus and amassed constitutional powers that established him as the first Roman emperor, inaugurating the Principate era of the Roman Empire.

Augustus also created nine special cohorts to maintain peace in Italia, with three, the Praetorian Guard, kept in Rome. Control of the fiscus enabled Augustus to ensure the loyalty of the legions through their pay.