Final answer:
The Roman form of government broke down after 133 BCE and resulted in a series of civil wars, which ended with Julius Caesar defeating Pompey and the Senate.
Step-by-step explanation:
The Roman form of government broke down after 133 BCE and resulted in a series of civil wars. These civil wars ended with Julius Caesar defeating Pompey and the Senate. After Pompey's defeat, he was assassinated in 44 BCE by his former supporters who considered Caesar a tyrant.