60 BCE- Caesar enters into a business/political agreement with Pompey and Crassus, known as The First Triumvirate.
58 BCE- Caesar leaves Rome with his legions and went to Gaul in defeating the tribes there and securing the borders of the provinces.
54 BCE- Crassus was killed in battle against the Parthians in and, that same year, Julia died in childbirth.
Oh no my daughter is dead
Pompey became the sole military and political power in Rome and had the senate declare Caesar’s governorship of Gaul terminated and, further, ordered him to return to Rome as a private citizen. This would mean Caesar could be prosecuted for his actions when he was consul.
Ceaser must pay
Rather than returning to Rome as a citizen, Caesar marched his army across the Rubicon River in 49 BCE and into the city of Rome. This was, essentially, an act of war. Pompey, knowing Caesar’s military strength, fled to Spain and then to Greece where he was defeated by Caesar’s much smaller force at the Battle of Pharsalus in 48 BCE.
He's coming I must go!
How dare he!
Caesar, arriving in Egypt in pursuit of Pompey, claimed outrage over Pompey’s death, proclaimed martial law, and took over the royal palace by marrying Cleopatra.