Historians usually date the beginning of the Roman Empire from 27 BC when the Roman Senate gave Gaius Octavius the name Augustus and he became the undisputed emperor after years of bitter civil war.
In Rome around 48 B.C, Caesar was appointed dictator, with Mark Antony as his Master of the Horse; Caesar resigned this dictatorate after 9 days and was elected to a second term as consul with Publius Servilius Vatia as his colleague.
He pursued Pompey to Alexandria, where Pompey was murdered by a former Roman officer serving in the court of King Ptolemy XIII. Caesar then became involved with the Alexandrine civil war between Ptolemy and his sister, wife, and co-regent queen, the Pharaoh Cleopatra VII.
Caesar defeated the Ptolemaic forces in 47 BC in the Battle of the Nile and installed Cleopatra as ruler, with whom he is suspected to have fathered a son, Caesarion.
On Caesar's return to Italy in September 45 BC, he filed his will, naming his grand-nephew Gaius Octavius (Octavian) as the heir to everything, including his title. Caesar also wrote that if Octavian died before Caesar did, Marcus Junius Brutus would be the next heir in succession.
Ancient biographers describe the tension between Caesar and the Senate, and his possible claims to the title of king. These events would be the principal motive for Caesar's assassination by his political opponents in the Senate.
Brutus began to conspire against Caesar and on the Ides of March (March 15) of 44 BC, a group of senators led by Brutus killed Julius Caesar.
In the ensuing chaos Mark Antony, Octavian (later Augustus Caesar), and others fought a series of five civil wars, which would end in the formation of the Roman Empire.
The young Octavius was adopted by his great uncle, Julius Caesar, and came into his inheritance after Caesar's assassination in 44 BC. The following year, Octavian joined forces with Mark Antony and Marcus Aemilius Lepidus in a military dictatorship known as the Second Triumvirate.
Antony and Octavian then sent 28 legions by sea to face the armies of Brutus and Cassius, who had built their base of power in Greece. After two battles at Philippi in Macedonia in October of 42 BC, the Caesarian army was victorious and Brutus and Cassius committed suicide.
After the battle, a new territorial arrangement was made between the members of the Second Triumvirate. While Antony would leave Gaul, the provinces of Hispania, and Italia in the hands of Octavian, Antony traveled east to Egypt where he allied himself with Queen Cleopatra VII, the former lover of Julius Caesar and mother of Caesar's infant son, Caesarion.
In 36 BC, Octavian used a political ploy to make himself look less autocratic and Antony more the villain by proclaiming that the civil wars were coming to an end, and that he would step down as triumvir if only Antony would do the same; Antony refused.
In the Battle of Actium in 31 B.C, Octavius defeated Cleopetra and Antony; Antony was killed and Cleopetra committed suice. And by murdering Cleopetra's son Caesarion, he reomoved all obstacles to his legitimacy to the throne of Roman Empire.
Marching into Rome, Octavian and Marcus Agrippa were elected as dual consuls by the Senate.
In 27 BC, Octavian officially returned democratic power to the Roman Senate and relinquished his control of the Roman provinces and their armies.
In January of 27 BC, the Senate gave Octavian the new titles of Augustus and Princeps. Augustus, from the Latin word Augere (meaning to increase), can be translated as "the illustrious one". It was a title of religious rather than political authority.
According to Roman religious beliefs, the title symbolized a stamp of authority over humanity—and in fact nature—that went beyond any constitutional definition of his status. After the harsh methods employed in consolidating his control, the change in name would also serve to demarkate his benign reign as Augustus from his reign of terror as Octavian.