When Caesar Augustus came to power, this form of government disappeared from Rome. monarchy republic oligarchy dictatorship

It was the Republic. The senators failed to gain the support of the Roman people of killing Julius Caesar and a power struggle took place where all the armies of the Republic were defeated by Mark Anthony, Octavian and Lepidus at the Battle of Philippi in 42 B. C. Later Anthony and Octavian fought at Actium where Anthony and Cleopatra were defeated and took their own lives. Octavian’s victory marked the end of the Republic and the start of the Empire of Rome where he was give the name Augustus.