Caesar's Civil War

Julius Caesar pausing on the banks of the Rubicon

In January, 49 BC, Caesar's opponents in the Senate, led by Lentulus, Cato and Scipio, tried to strip Caesar of his command (provinces and legions) and force him to return to Rome as a private citizen (liable to prosecution). Caesar's allies in the Senate, especially Mark Anthony, Curio, Cassius and Caelius Rufus, tried to defend their patron, but were threatened with violence. On 7 January the Senate passed the consultum ultimum (declaring a state of emergency) and charged the consuls, praetors, tribunes and proconsuls with the defence of the state. That night Anthony, Cassius, Curio and Caelius Rufus fled from Rome and headed north to join Caesar.[7]

On January 10, 49 BC, commanding the Legio XIII, Caesar crossed the Rubicon River, the boundary between the province of Cisalpine Gaul to the north and Italy proper to the south. As crossing the Rubicon with an army was prohibited, lest a returning general attempt a coup d'etat, that triggered the ensuing civil war between Caesar and Pompey.

The general population, which regarded Caesar as a hero, approved of his actions. The historical records differ about the decisive comment Caesar that made on crossing the Rubicon: one report is Alea iacta est (usually translated as "The die is cast").

Caesar's own account of the Civil War makes no mention of the river crossing but simply states that he marched to Rimini, a town south of the Rubicon, with his army.[8]

Column of Julius Caesar, where he addressed his army to march on Rome and start the Civil War, Rimini, Italy

Within a week of passing the consultum ultimum (declaring a state of emergency and outlawing Caesar) news reached Rome that Caesar had crossed the Rubicon (10 January) and had taken the Italian town of Ariminum (12 January).[9] By January 17 Caesar had taken the next three towns along the Flaminian Way, and that Marcus Anthonius (Mark Anthony) had taken Arretium and controlled the Cassian Way.[9] The Senate, not knowing that Caesar possessed only a single legion, feared the worst and supported Pompey, who declared that Rome could not be defended. He escaped to Capua with those politicians who supported him, the aristocratic Optimates and the regnant consuls. Cicero later characterised Pompey's "outward sign of weakness" as allowing Caesar's consolidation of power.

Despite having retreated into central Italy, Pompey and the Senatorial forces were composed of at least two legions: some 11,500 soldiers and some hastily-levied Italian troops commanded by Lucius Domitius Ahenobarbus. As Caesar progressed southwards, Pompey retreated towards Brundisium, initially ordering Domitius (engaged in raising troops in Etruria) to stop Caesar's movement on Rome from the direction of the Adriatic seaboard.

Belatedly, Pompey requested Domitius to retreat south to rendezvous with Pompey's forces. Domitius ignored Pompey's request believing he outnumbered Caesar three to one. Caesar, however, had been reinforced by two more legions from Gaul (the eighth and the twelfth) and twenty-two cohorts of recruits (recruited by Curio) and in fact outnumbered Domitius five to three. Domitius after being isolated and trapped near Corfinium, was forced to surrender his army of thirty-one cohorts (about three legions) following a brief siege. With deliberate clemency, Caesar released Domitius and the other senators with him and even returned 6,000,000 sesterces that Domitius had had to pay his troops. The thirty-one cohorts, however, were made to swear a new oath of allegiance to Caesar and were eventually sent to Sicily under the command of Asinius Pollio.[10] Caesar now had three veteran legions and fifty-three cohorts of recruits at Corfinium. The Caesarian army in Italy now outnumbered the republicans (8:5) and Pompey knew the peninsula was lost for the time being.

Pompey escaped to Brundisium, there awaiting sea transport for his legions, to Epirus, in the Republic's eastern Greek provinces, expecting his influence to yield money and armies for a maritime blockade of Italy proper. Meanwhile, the aristocrats, including Metellus Scipio and Cato the Younger, joined Pompey there and left a rear guard at Capua.

Caesar pursued Pompey to Brundisium, expecting restoration of their alliance of ten years earlier. Throughout the Great Roman Civil War's early stages, Caesar frequently proposed to Pompey for both generals to sheathe their swords. Pompey refused, legalistically arguing that Caesar was his subordinate and so was obligated to cease campaigning and dismiss his armies before any negotiation. As the Senate's chosen commander and with the backing of at least one of the current consuls, Pompey commanded legitimacy, but Caesar's military crossing of the Rubicon rendered him a de jure enemy of the Senate and the people of Rome. Caesar then tried to trap Pompey in Brundisium by blocking up the harbour mouth with earth moles from either side, joined across the deepest part by a string of rafts, each nine metres square, covered with a causeway of earth and protected with screens and towers. Pompey countered by constructing towers for heavy artillery on a number of merchant ships and used them to destroy the rafts as they were floated in position. Eventually, in March 49 BC, Pompey escaped and fled by sea to Epirus, leaving Caesar in complete command of Italy.[11]

Taking advantage of Pompey's absence from the Italian mainland, Caesar marched west to Hispania. Onroute he started the Siege of Massilia. Within 27 days after setting out he arrived on the Iberian peninsula. At Ilerda he defeated the politically-leaderless Pompeian army, commanded by the legates Lucius Afranius and Marcus Petreius. Afterwards pacifying Roman Hispania.

Returning to Rome in December of 49 BC, Caesar was appointed dictator, with Mark Antony as his Master of the Horse. Caesar kept his dictatorship for eleven days, a tenure sufficient to win him a second term as consul with Publius Servilius Vatia Isauricus as his colleague. Afterwards, Caesar renewed his pursuit of Pompey in Greece.

From Brundisium, Caesar crossed the Strait of Otranto with seven legions to the Gulf of Valona (not Palaesta in Epirus [modern Palase/Dhermi, Albania], as reported by Lucan),[12] prompting Pompey to consider three courses of action: (i) to make an alliance with the King of Parthia, an erstwhile ally, far to the east; (ii) to invade Italy with his superior navy and/or (iii) to force a decisive battle with Caesar. A Parthian alliance was not feasible since a Roman general fighting Roman legions with foreign troops was craven, and the military risk of an Italian invasion was politically unsavoury because the Italians, who thirty years earlier had rebelled against Rome, might rise against him. Thus, on the advice of his councillors, Pompey decided to engineer a decisive battle.

As it turned out, Pompey would have been obliged to take the third option anyway, as Caesar had forced his hand by pursuing him to Illyria and so on 10 July 48 BC, the two fought in the Battle of Dyrrhachium. With a loss of 1,000 veteran legionaries, Caesar was forced to retreat southwards. Refusing to believe that his army had bested Caesar's legions, Pompey misinterpreted the retreat as a feint into a trap and so did not give chase to deliver the decisive coup de grâce, thus losing the initiative and his chance to conclude the war quickly. Near Pharsalus, Caesar pitched a strategic bivouac. Pompey attacked but, despite his much larger army, was conclusively defeated by Caesar's troops. A major reason for Pompey's defeat was miscommunication among front cavalry horsemen.

Pompey fled to Egypt, where he was murdered by an officer of King Ptolemy XIII. Caesar pursued the Pompeian army to Alexandria, where he camped and became involved with the Alexandrine Civil War between Ptolemy and his sister, wife and co-regent, Cleopatra VII. Perhaps as a result of Ptolemy's role in Pompey's murder, Caesar sided with Cleopatra and is reported to have wept at the sight of Pompey's head, which was offered to him by Ptolemy's chamberlain, Pothinus, as a gift.

In any event, Caesar was besieged at Alexandria and after Mithridates relieved the city, Caesar defeated Ptolemy's army and installed Cleopatra as ruler with whom he fathered his only known biological son, Ptolemy XV Caesar, better known as "Caesarion". Caesar and Cleopatra never married because Roman law prohibited a marriage with a non-Roman citizen.

After spending the first months of 47 BC in Egypt, Caesar went to Syria and then to Pontus to deal with Pharnaces II, Pompey's client king who had taken advantage of the civil war to attack the Roman-friendly Deiotarus and to make himself the ruler of Colchis and lesser Armenia. At Nicopolis Pharnaces had defeated what little Roman opposition the governor of Asia, Gnaeus Domitius Calvinus, could muster. He had also taken the city of Amisus, which was a Roman ally; made all the boys eunuchs and sold the inhabitants to slave traders. After the show of strength, Pharnaces drew back to pacify his new conquests.

Nevertheless, the extremely-rapid approach of Caesar in person forced Pharnaces to turn his attention back to the Romans. At first, recognising the threat, he made offers of submission with the sole object of gaining time until Caesar's attention fell elsewhere. It was to no avail since Caesar quickly routed Pharnaces at the Battle of Zela (modern Zile in Turkey) with just a small detachment of cavalry. Caesar's victory was so swift and complete that in a letter to a friend in Rome, he famously said of the short war, "Veni, vidi, vici" ("I came, I saw, I conquered"). Indeed, for his Pontic triumph, that may well have been the label displayed above the spoils.

Pharnaces himself fled quickly back to the Bosporus, where he managed to assemble a small force of Scythian and Sarmatian troops with which he was able to gain control of a few cities, but one of his former governors, Asandar, attacked his forces and killed him. The historian Appian states that Pharnaces died in battle, but Cassius Dio says that Pharnaces was captured and then killed.

While Caesar had been in Egypt and installed Cleopatra as sole ruler, four of his veteran legions encamped, under the command of Mark Antony. The legions were waiting for their discharges and the bonus pay that Caesar had promised them before the Battle of Pharsalus. As Caesar lingered in Egypt, the situation quickly deteriorated. Antony lost control of the troops, who began looting estates south of the capital. Several delegations of diplomats were dispatched to try to quell the mutiny.

Nothing worked, and the mutineers continued to call for their discharges and back pay. After several months, Caesar finally arrived to address the legions in person. Caesar knew that he needed the legions to deal with Pompey's supporters in North Africa since the latter had mustered 14 legions. Caesar also knew that he did not have the funds to give the soldiers their back pay, much less the money needed to induce them to re-enlist for the North African campaign.

When Caesar approached the speaker's dais, a hush fell over the mutinous soldiers. Most were embarrassed by their role in the mutiny in Caesar's presence. He asked the troops what they wanted with his cold voice. Ashamed to demand money, the men began to call out for their discharge. Caesar bluntly addressed them as "citizens", instead of "soldiers," a tacit indication that they had already discharged themselves by virtue of their disloyalty.

He went on to tell them that they would all be discharged immediately. He said that he would pay them the money that he owed them after he won the North African campaign with other legions. The soldiers were shocked since they had been through 15 years of war with Caesar and they had become fiercely loyal to him in the process. It had never occurred to them that Caesar did not need them.

The soldiers' resistance collapsed. They crowded the dais and begged to be taken to North Africa. Caesar feigned indignation and then allowed himself to be won over. When he announced that he would allow them to join the campaign, a huge cheer arose from the assembled troops. Through that reverse psychology, Caesar re-enlisted four enthusiastic veteran legions to invade North Africa without spending a single sesterce.

Caesar quickly gained a significant victory at the Battle of Thapsus in 46 BC over the forces of Metellus Scipio, Cato the Younger and Juba, who all committed suicide.

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. Meanwhile, Caesar had been elected to his third and fourth terms as consul in 46 BC (with Marcus Aemilius Lepidus) and 45 BC (sine collega, without a colleague).