50a alea iacta est the dis is cast

 Caesar's civil war

n 50 BC, the Senate, led by Pompey, ordered Caesar to disband his army and return to Rome because his term as Proconsul had finished.^[30] Moreover, the Senate forbade Caesar to stand for a second consulship in absentia.^[30] Caesar thought he would be prosecuted and politically marginalised if he entered Rome without the immunity enjoyed by a Consul or without the power of his army. Pompey accused Caesar of insubordination and treason. On 10 January 49 BC Caesar crossed theRubicon river (the frontier boundary of Italy) with only one legion and ignited civil war. Upon crossing the Rubicon, Plutarch reports that Caesar quoted the Athenian playwright Menander in Greek, saying anerrhiphthō kubos (ἀνερρίφθω κύβος; let the dice be tossed).^[31] Suetonius gives the Latin approximation alea iacta est (the die has been tossed).^[32]

The Optimates, including Metellus Scipio and Cato the Younger, fled to the south, having little confidence in the newly raised troops especially since so many cities in northern Italy had voluntarily surrendered. An attempted stand by a consulate legion in Samarium resulted in the consul being handed over by the defenders and the legion surrendering without significant fighting. Despite greatly outnumbering Caesar, who only had his Thirteenth Legion with him, Pompey had no intention of fighting. Caesar pursued Pompey to Brindisium, hoping to capture Pompey before the trapped Senate and their legions could escape.^[33] Pompey managed to elude him, sailing out of the harbour before Caesar could break the barricades.

Having near no naval force since Pompey had already scoured the coasts of all ships for evacuation of his forces, Caesar decided to head for Hispania saying "I set forth to fight an army without a leader, so as later to fight a leader without an army." Leaving Marcus Aemilius Lepidus as prefect of Rome, and the rest of Italy underMark Antony as tribune, Caesar made an astonishing 27-day route-march to Hispania, rejoining two of his Gallic legions, where he defeated Pompey's lieutenants. He then returned east, to challenge Pompey in Greece where on 10 July 48 BC at Dyrrhachium Caesar barely avoided a catastrophic defeat when the line of fortification was broken. He decisively defeated Pompey, despite Pompey's numerical advantage (nearly twice the number of infantry and considerably more cavalry), at Pharsalus in an exceedingly short engagement in 48 BC.^[34]

In Rome, Caesar was appointed dictator,^[35] with Mark Antony as his Master of the Horse; Caesar presided over his own election to a second consulate (with Publius Servilius Vatia as his colleague) and then, after eleven days, resigned this dictatorate

He pursued Pompey to Alexandria, where Pompey was murdered by a former Roman officer serving in the court of King Ptolemy XIII.^[37] Caesar then became involved with the Alexandrine civil war between Ptolemy and his sister, wife, and co-regent queen, the Pharaoh Cleopatra VII. Perhaps as a result of Ptolemy's role in Pompey's murder, Caesar sided with Cleopatra; he is reported to have wept at the sight of Pompey's head,^[38] which was offered to him by Ptolemy's chamberlain Pothinus as a gift. In any event, Caesar withstood the Siege of Alexandria and latter he defeated the Ptolemaic forces in 47 BC in the Battle of the Nile and installed Cleopatra as ruler. Caesar and Cleopatra celebrated their victory of the Alexandrine civil war with a triumphant procession on the Nile in the spring of 47 B.C. The royal barge was accompanied by 400 additional ships, introducing Caesar to the luxurious lifestyle of the Egyptian pharaohs.

Caesar and Cleopatra never married, as Roman Law only recognised marriages between two Roman citizens. Caesar continued his relationship with Cleopatra throughout his last marriage, which lasted 14 years – in Roman eyes, this did not constitute adultery – and may have fathered a son called Caesarion. Cleopatra visited Rome on more than one occasion, residing in Caesar's villa just outside Rome across the Tiber.

Late in 48 BC, Caesar was again appointed Dictator, with a term of one year.^[36] After spending the first months of 47 BC in Egypt, Caesar went to the Middle East, where he annihilated King Pharnaces II of Pontus in the Battle of Zela; his victory was so swift and complete that he mocked Pompey's previous victories over such poor enemies.^[39] Thence, he proceeded to Africa to deal with the remnants of Pompey's senatorial supporters. He quickly gained a significant victory at Thapsus in 46 BC over the forces of Metellus Scipio (who died in the battle) and Cato the Younger (who committed suicide).^[40] After this victory, he was appointed Dictator for ten years.^[41]

Nevertheless, Pompey's sons Gnaeus Pompeius and Sextus Pompeius, together with Titus Labienus, Caesar's former propraetorian legate (legatus propraetore) and second in command in the Gallic War, escaped to Hispania. Caesar gave chase and defeated the last remnants of opposition in the Battle of Munda in March 45 BC.^[42] During this time, Caesar was elected to his third and fourth terms as consul in 46 BC (with Marcus Aemilius Lepidus) and 45 BC (without colleague).