How was Augustus related to Julius Caesar?

Augustus, known as Caesar Augustus or Octavian, was the Roman emperor Julius Caesar's great-nephew whom he adopted as his son and heir.

By the middle of the first century BCE, Julius Caesar desperately needed an heir. He had no son, but he did have a daughter, Julia. Married several times, the last time to Caesar's longtime rival and friend Pompey, Julia sadly died in childbirth in 54 BCE.

So, as was common in ancient Rome then and later, Caesar sought his closest male relative to adopt as his own son. In this case, the lad in question was young Gaius Octavius, whom Caesar took under his own wing in the final years of his life.

By taking his great–uncle's name, Octavian also assumed Caesar's political mantle at the young age of 18. While Julius Caesar was, in fact, a great leader, general, and dictator, he was not an emperor. In fact, he was in the process of instituting major political reforms when he was assassinated by Brutus and other members of the Roman Senate.