The reign of this husband of Livia saw the beginning of the Pax Romana, which began shortly after this member of the (*) Second Triumvirate defeated the fleet of Marc Antony and Cleopatra at Actium and changed his name from Octavian.
Quintus Dellius defected to this man's side prior to a 31 BCE battle in the Ionian Sea. The reign of this husband of Livia saw the beginning of the Pax Romana, which began shortly after this member of the (*) Second Triumvirate defeated the fleet of Marc Antony and Cleopatra at Actium and changed his name from Octavian. For 10 points, name this first Emperor of Rome, the namesake of the eighth month of the modern calendar.
Quintus Dellius defected to this man's side prior to a 31 BCE battle in the Ionian Sea.
Augustus Caesar (or Octavian; prompt on Caesar; do not accept or prompt Julius Caesar)