Julius Caesar was a general in the Roman army who was rapidly rising in power. He had captured the Gaul area and impressed many people, but he also made some enemies. However, his once unbreakable alliance with Pompey the Great had become a rivalry about who could rise and claim the most power. Pompey convinced the Roman Senate to command Caesar to give up his soldiers and army and return to Rome as a civilian. Caesar didn’t even consider this command, he gathered his men, crossed the Rubicon Valley(basically a border that leads into Rome) and created a civil war. When Caesar used his few but smart troops to his advantage and won the Battle of Pharsalus, Pompey knew he had lost the war to Caesar. He escaped to Egypt, only to be betrayed by its king and face execution. After Pompey's death, Caesar defeated his remaining allies and returned to Rome to be named dictator for life, but his reign would be very short.
This image depicts the war between Caesar and Pompey.