Final answer:
Pompey was the Roman general who fought a civil war against Julius Caesar. They were initially allies in the First Triumvirate but later became enemies, leading to the Great Roman Civil War, which marked the end of the Roman Republic and Pompey's defeat. The correct option is 1.
Step-by-step explanation:
The Roman general who fought a civil war with Julius Caesar was Pompey. In the political alliance known as the First Triumvirate, Pompey, along with Crassus and Caesar, sought to dominate Roman politics.
However, after Crassus's death, the alliance dissolved, and Pompey joined forces with the conservative optimates to oppose Caesar. Caesar's growing power and popularity, stemming in part from his military successes in Gaul, were viewed as a threat by the Senate and Pompey.
The conflict escalated when Caesar crossed the Rubicon in 49 BCE, initiating the Great Roman Civil War, which ended in Pompey's defeat. Pompey fled to Egypt where he was subsequently murdered, and Caesar became the dominant political force in Rome until his assassination in 44 BCE.