Question

What marked the official transition from Roman republic to Roman Empire

Answer 1

When Augustus, formally known as Octavian became Emperor of Rome

Step-by-step explanation:

With the conclusion of the Battle of Philippi in 42 BC, Augustus and his cohorts dissolved the Roman Republic. This marked the beginning of the Roman Empire which was ruled by Augustus until his death in AD 14.

Answer 2

So in the first century of BC, Rome was a republic -- but eventually, senators began fighting for power between themselves and the republic soon fell into chaos. Two men, one of which were Julius Caesar, were able to wrestle Rome back from chaos and rule in their empires. Though he was murdered and his rule was brief, it marked the official transition from Roman Republic to Roman Empire.