In the year 44 BC, when Julius Caesar was killed, Augustus was a mere teenager who had been adopted into Caesar's household. His reaction to Caesar's death was to step forward and proclaim himself Caesar's rightful successor. The Senate did not take him seriously, but over the following months he raised his own army and, after defeating Mark Antony in battle, became one of the three most powerful men in Rome. He was not yet 20 years old. Over the next ten years he consolidated his power, and finally overthrew the last of his rivals in 31 BC. From that moment on Rome became an empire, and Augustus its first emperor. This is the story of how one man rose to become the most powerful man in the world, and stabilised an empire that had been racked by decades of civil war.