In the midst of his civil war ( October of 48BC) Julius Caesar found himself seriously entangled in the court intrigues of the Egyptian monarchy. In addition to the complicated political situation that he was facing in Egypt he also had to deal with a local uprising that turned out to be quite serious. The Egyptians were instigated by local officials to revolt against the Roman presence and they actually besieged Caesar within the city of Alexandria for almost 6 months, causing some serious distress to the Roman general who only had the meagre force of a single legion accompanying him. While Caesar was seriously engaged with the Egyptian affairs and being under siege, an old enemy of Rome, began rampaging through lesser Armenia and Cappadocia. 

It was the king of Pontus who during that Period was Pharnaces the second, the son of Mithridates Eupator one of the great and most successful enemies of Rome. Caesar had left in charge of the province of “Asia” his faithful lieutenant, Domitius calvinus who was informed about the incursions of Pharnaces by a local king and an ally of the Romans, Deiotarus.

 King Deiotarus send a letter to Domitius beseeching him "not to allow Pharnaces to occupy and lay waste to Cappadocia and Lesser Armenia that were both areas that belonged to kings who were allies and friends of the Roman people. Domitius could not afford the disgrace or financial impact that the loss of those areas would cause, especially during the stretch that was imposed upon the Roman administration due to the civil strife. So he send embassies to Pharnaces ordering him to immediately evacuate the areas that belonged to esteemed allies of the Romans. 

Calvinus, believing that his deputation would have greater weight if he was ready to backup his demands with himself at the head of an army, he made extensive preparations and after having gathered around 4 legions, 200 cavalry and a few auxiliaries from Cilicia, he concentrated these forces at the city of Comana. Those forces included one newly recruited legion from local levies, another legion that was recruited and trained by king Deiotarus and the veteran legion of ex Pompeiians, the 36th. Marching along a woody ridge of hills that led to Pontus, Domitius Calvinus all the while received several messages and gifts from Pharnaces who requested peace but insisted on keeping possession of lesser Armenia by right of inheritance. Domitius denied all of Pharnace’s requests rendering a clash inevitable. 

After a series of long marches Domitius eventually reached the city of Nicopolis and there he set his camp just seven miles away from the city. Between the city and the his camp lay a narrow pass that Pharnaces intended to block, after further attempts for a peaceful conclusion by Pharnaces were rejected, Domitius marched with his army closer to the city and encamped just outside the entrance of the narrow pass. Pharnaces dug two trenches that covered the front of his formation and another covering his rear and with his army deployed in battle formation endeavoured to block the advance of Calvinus’s legions. Soon afterwards the two armies clashed and a desperate struggle ensued, the right wing of Domitius that was occupied by the veterans of the 36th legion was successful and managed to drive their counterpart from the field but the centre and the left wing of Calvinus’s army disintegrated in front of the Pontic charge.

 The battle soon turned into a roman rout and only the veterans of the 36th legion managed to survive with minimum casualties by retreating in an orderly fashion to the foot of a nearby mountain.(date December 48) The triumph at Nicopolis emboldened the Pontic king and shortly after the defeat of Domitius Calvinus, Pharnaces entered and occupied Pontus as there was no one left to oppose him, while committing all sorts of atrocities against Roman and Pontic citizens that were, reportedly, “worst than death for the Romans”.

 In February of 47BC Caesar was finally victorious against the Egyptians at the Battle of the Nile. After a brief hiatus to his usual ceaseless activity, he departed from Egypt to Syria. There he redressed the state of the province restoring order and freeing it from domestic contentions. 

After settling affairs there he sailed from Syria to Cilicia with the fleet he brought with him from Egypt and in Tarsus he assembled all of the allied potentates, kings and rulers of the nearby areas and reassured their allegiance to him and the Roman state and in a hasty and eager manner advanced through Cappadocia to Comana while simultaneously settling disputes and restoring the state of affairs of the surrounding regions and kingdoms. Upon approaching Pontus and the frontiers of Gallograecia Deiotarus, the King of the Area and of lesser Armenia, that was occupied by Pharnaces at the time, came in a suppliant manner to beg Caesar for forgiveness for assisting Pompey Caesar forgave Deiotarus and commanded him to join him with all his cavalry and the remnants of the legion that he had trained in the Roman manner. When he arrived in Pontus Caesar drawn all of his forces together. 

In total his forces were composed by the remnants of the veteran VI legion which he brought with him from Egypt and numbered barely 1000 men, the legion of Deiotarus, two more legions that fought against Pharnaces during the battle of Nicopolis and a contingent of cavalry that was also brought by Deiotarus. Pharnaces all the while kept sending ambassadors to Caesar requesting peace and seeking a mutual agreement with the Roman general, pointing out that Pharnaces didn’t assist Pompey as Deiotarus did, whom he nonetheless pardoned.

 Caesar replied that he should immediately abandon the lands that he had occupied and restore to the Romans and their allies what he unjustly detained from them, while reminding him that he could neither bring back the dead nor he could restore manhood to those he had deprived of it, a punishment that he described as being worse for the Romans than even death. While Pharnaces seemingly accepted the ultimatum he however tried to protract the negations and made further demands, it is implied by our sources that the Pontic King did this in order to delay Caesars departure from Asia in the hope that this distraction would complicate even further the precarious political situation that was developing back in Rome.

 Caesar sensed this and decided to quickly resolve the situation with Pharnaces by a battle. He advanced with his army and encamped just 5 miles away from the town of Zela, a town of Pontus that was situated in a plain but surrounded by relatively high mountains from all sides. The highest of these mountains was intersected by a narrow valley, a location that was renowned for a victory that Pharnaces’s father, Mithridates, achieved against the Romans a few years . 

It was at that place that Pharnaces encamped with all of his forces and began repairing the old fortifications of a position that proved so fortunate to his father. From his position Caesar saw the eminences that were defending the kings camp and realized that this position could be likewise used to his own advantage, during that same night he mobilized both his legionaries and the servants that were following the army, marched them through the narrow valley and occupied an eminence overlooking the position of his enemy, then at day brake and without stopping for a moment he set both his legionaries and the servants to fortify the elevated position. Pharnaces soon perceived Caesars movement and not long after he arrayed his entire army in order of battle in front of his camp on the narrow valley that did not exceed a mile in length, which was located between the two fortifications.

 His exact deployment is not known but we can assume that it would not have been much different than it was during the battle of Nicopolis, with a thin line of tribal and locally recruited infantry in the centre and his numerous cavalry at his flanks, Pharnaces also deployed a force of scythed chariots, that were probably positioned in front of his main formation. In total his army numbered around 20.000 men. Caesar observed his enemy’s deployment but he did not believe that Pharnaces had any intention to advance against him, given the extremely disadvantageous nature of the ground and the narrow space in which he had crowded his army. He initially thought that Pharnaces was just reviewing his troops and was trying to keep a large portion of the Romans under arms so as to delay their fortifications. Despite the topographic impossibility, Pharnaces advanced with his army straight towards the elevated entrenched roman position. 

When Caesar observed this he laughed at his ostentation and still thought that no man in his right mind would have dared to advance against such odds. But in the meantime Pharnaces’s army continued its march and began to ascend the steep hill on which Caesar was posted. If Pharnaces achieved anything during that morning of August 47BC was to completely astonish and surprise Julius Caesar who in disbelief found himself suddenly and unexpectedly charged with his army not being properly arranged to fend off the attack.

 He quickly called off his soldiers from the works and ordered them in battle formation. The rashness and audacity of the attack almost caught the Romans off guard and initially Pharnaces managed to cause some terror and confusion to the Roman ranks since they weren’t properly formed yet. The scythed chariots somehow managed to cause some disruption despite attacking against an inclined position, but they were eventually driven back by the multitude of arrows and pila that were thrown against them. 

The rest of the enemy army followed them closely and began the battle with a shout, the two armies engaged in a swift and sharp conflict, with the roman lines still forming up. Due to the ardour of Pharnaces’s charge things seemed to be hanging in the balance at first, but after the legions managed to absorb the initial charge of the enemy and with the steady flow of reinforcements constantly arriving from the main camp to aid their comrades in the front line, the advance of the Pontic army came to a total halt. 

The breakthrough first came on the Roman right wing where the veteran 6th legion was posted, that managed to brake the opposing enemy left wing. In the centre and left wing the battle raged on for a little longer, but given the extreme topographic disadvantage that their king had placed them in, the Pontic troops were soon driven back down the same hill that they so easily ascended before. 

The retreat turned into a massive disorganized and panicky rout and due to the extremely inclined nature of the ground the retreating mass of soldiers crashed many thousands of their comrades during their flight. 

Those who survived the initial onslaught retreated back the way they came, crossed the narrow valley and got up the opposite ascend were their camp was located. While the romans were being hot on their heels most of them were obliged to throw down their weapons, so when the Romans caught up with them to their camp there was little they could do to defend themselves. 

The Roman army flushed with victory did not hesitate to attack despite the disadvantageous ground and they soon forced their way inside the enemy fortifications. The exact casualties for both sides are unknown but it is mentioned that most of the army of Pharnaces was either killed or captured during the battle, while Pharnaces himself managed to escape with a small contingent of his cavalry. The Romans loses were probably negligible. 

Zela was a decisive victory for Caesar, it was a campaign that he thought would delay him for months but it was instead resolved within just a few days. After he dealt with the crisis that unfolded in Asia minor following the defeat of Domitius Calvinus, the Roman general departed for Rome, where a serious political situation was developing and required his immediate attention In announcing the swiftness and decisiveness of this victory to one of his friends at Rome, Caesar wrote the now famous three words, “Veni, Vidi, Vici”. ( I came I saw I conquered) Notwithstanding this triumph, Julius Caesar was still in the midst of the largest civil war of the ancient world and the direst clashes of this conflict were yet to come.