Battle of Zela; "Veni, vidi, vici;" Julius Caesar Defeats Pharnaces of Pontus

« Previous story
Next story »
Battle of Zela; "Veni, vidi, vici;" Julius Caesar Defeats Pharnaces of Pontus

Julius Caesar rallying his Roman forces, battle of Zela; artist unknown
Image courtesy of
(Unless otherwise indicated, all illustrations are courtesy of Wikipedia)

Today in Military History: May 21, 47 BC

If not for Julius Caesar's pithy, laconic comment on this battle, it would probably be little more than a footnote in the history of the Roman Civil War of the late first century BC. However, it is still worth of consideration for my weekly mini-military history lesson.


Marble bust of Julius Caesar (known as the
Marble bust of Julius Caesar (known as the "Tusculum bust")
It is believed to have been executed during his lifetime
On display at the Museo d'Antichità in Turin, Italy

As the Roman Civil War was winding down, Caesar travelled to Egypt in pursuit of a defeated Pompey the Great, his rival for power in the Roman Republic. In addition, Caesar took it upon himself to settle a dynastic struggle between Ptolemy XIII and his sister and co-ruler Cleopatra. Arriving in Egypt in February of 47 BC, the Roman forces were temporarily besieged in Alexandria, but Caesar defeated the Egyptians. Asiatic reinforcements commanded by Mithridates of Pergamum, son of Mithridates VI of Pontus and a Roman client, came to his assistance, and the Roman-Asiatic force defeated the Ptolemaic forces at the Battle of the Nile in early April.

After defeating the Ptolemaic rebels and resolving the succession to the Egyptian throne in Cleopatra's favor, Caesar received intelligence that another Roman client, Pharnaces II of Pontus, had broken his oath of fealty to the Roman Republic.

Pharnaces had been appointed ruler of the Bosporan Kingdom (the modern-day Crimean peninsula) by Pompey the Great. The Asiatic monarch took advantage of the conflict between Caesar and Pompey. Whilst the Romans were distracted by this conflict, Pharnaces decided to seize the opportunity and, with the forces under his disposal and against little opposition, made himself the ruler of the city-state of Colchis, and invaded and took control of Galatia. The ruler of the province of Galatia appealed to Gnaeus Domitius Calvinus, Caesar's lieutenant in Asia, for support, and soon the Roman forces sought battle with Pharnaces. They met in December of 48 at Nicopolis in Anatolia, where Pharnaces defeated the Roman army and overran Pontus and threatening to conquer the remainder of Asia Minor.

Kingdom of Pontus, at largest extent under Pharnaces II, c. 47 BC; Original territory (light purple), conquests before Zela (dark purple)
Kingdom of Pontus, at largest extent under Pharnaces II, c. 47 BC
Original territory (light purple), conquests before Zela (dark purple)

Prelude to the Battle

When Caesar received news of the Roman defeat at Nicopolis, he began hasty preparations to oppose Pharnaces and win back the lands lost to the Pontic monarch. He gathered what troops he could from his forces which had weathered the siege of Alexandria and participated in the Battle of the Nile. Caesar integrated a few of Mithridates of Pergamum's units into his force. The Romans marched through Judaea into Syria, accepting apologies and granting pardons to those foreign kings and Roman governors who had supported Pompey during the Roman Civil War. In so doing, Caesar was also able to rebuild his war chest through the various tributes paid to him. Caesar paused at Antioch to gather more troops from the Roman forces in that province.

Boarding ship in Syria, Caesar next sailed to Tarsus in Cilicia where he called a meeting of the regional leaders. Securing loyalty once again and laying out his plan of action, Caesar continued the march north through Cilicia, Cappadocia, and Galatia to Pontus. In addition to handing out pardons and accepting tribute, Caesar recruited some more troops, including some Galatian tribesmen, into his army.

Caesar continued his march until about mid-May when his decidedly ragtag force reached the vicinity of the town of Zela. [This town had decidedly bad memories for the Roman military establishment, as twenty years before, a Roman army was badly defeated by a Pontic army led by MIthridates VI – the father of Pharnaces – during the Third Mithridatic War (73-63 BC)].

Arriving near Zela on May 20, Caesar ordered his men to build a fortified camp (as was common Roman practice when an army was on the offensive). Shortly afterwards, he received a shock. Apparently, Pontic scouts had detected the approach of the Roman army. Pharnaces advanced to meet his Roman enemy. The Pontic force had camped on a large hill about 5 miles northwest of the town. Caesar's scouts found a similar hill across the valley from the Pontic encampment. The following morning, prior to sunrise, Caesar ordered his men forward to the new campsite and to construct their usual fortified encampment. He did not anticipate the Pontic army making an assault upon his army.

Roman Army

Caesar's army at Zela, totaling 10,000-11,000 men, was primarily composed of:

  • His full-strength Legio XXII (Twenty-second Legion);
  • Two cohorts (about 1000 legionaries) of his battle-ravaged Legio VI Ferrata (Sixth Legion);
  • An allied force of Galatians, descendants of Gallic warriors who invaded and settled in Asia Minor in the mid-third century BC, thus the origin of the area known as Galatia;
  • Some small contingents (called vexillations) from Legio XXXVI (Thirty-sixth Legion), which had been badly mauled by Pharnaces at Nicopolis; and,
  • A small cavalry contingent, possibly including Sarmatian or Armenian heavy horsemen courtesy of Mithridates, but certainly Gallic-Germanic cavalry with personal loyalty to Caesar.


Pontic Army

Pharnaces had an army of about 20,000 men, twice the size of Caesar's force. Many of them were tribal and levied infantry, but he did have professional legionaires (native Bosporian footmen trained in imitation of Roman legionaries), a solid core of pike-armed phalangites, javelin-armed skirmishers, and a mixture of heavy, medium, and light cavalry.

Pontic scythed chariot, c. 50 BC; Image courtesy of
Pontic scythed chariot, c. 50 BC
Image courtesy of

One unique unit in the Pontic army was scythed chariots, a holdover from the Persian military which fought Alexander the Great's Greco-Macedonian and Successor armies (from about 338-148 BC). [The scythed chariots never became the battle-deciders they were envisioned to be, more of a terror weapon.]

Battle of Zela

On the morning of May 21, activity was noticed in the Pontic camp. The army of Pharnaces marched out of the camp, and arranged itself with parade ground efficiency, as if for a review. Fearing a subterfuge, Caesar ordered a small number of his men to line up in a similar manner. The rest of his men he send back to constructing the camp.

As work on the Roman camp continued, an unusual thing occurred. The first elements of the Pontic army were sighted crossing the valley between them. Within minutes, the Asiatic forces were charging up the hill occupied by the Roman army. [In one history, Caesar is described as laughing at the foolhardy attempt of the Pontic army to attack his camp up the rough slope of the hill his men now occupied.]

Though not caught completely flat-footed by the sudden enemy onslaught, the Roman soldiers were temporarily confused and disordered. However, the veteran Roman legionaries of the Sixth, Twenty-first, and Thirty-sixth legions, as well as the Gallic-German cavalry, quickly retrieved their weapons and deployed for battle.

The Pontic army, though outnumbering Caesar's force by two to one, had made one fatal mistake; a pike phalanx army such as commanded by Pharnaces was best deployed on level ground. Hilly terrain caused the usually disciplined lines to break apart on their own, causing gaps which any competent general (like Julius Caesar) could exploit. In addition, the Pontic scythed chariots were next to useless in hilly terrain. The Roman troops initially contacted by the chariots used their pila (javelins) to dispatch the horses, putting most of the machines out of the battle.

The battle quickly turned into a fierce, bloody hand-to-hand melee. Although badly outnumbered, the Romans had one ace up their sleeve: Gaius Julius Caesar. He had fought wars throughout the known world; from Spain to Egypt, from North Africa to Gaul. His conquest of Gaul – culminating with the siege of Alesia in 52 BC – was a strategic and tactical masterpiece.

Roman cohort (foreground) attacking block of Pontic pikemen; Image courtesy of
Roman cohort (foreground) attacking block of Pontic pikemen
Image courtesy of

Caesar had anticipated the Pontic assault, and made preparations. Most importantly, he was a great believer in a general's personal involvement on the battlefield. In almost every major battle of his career, Caesar instinctively knew when it was necessary for him to fight in the front ranks. He knew it was important for his legionaries to know that their commander was sharing their dangers.

After about an hour or two of heavy fighting, the Roman right wing – comprised of the soldiers of Legio VI – overcame the Pontic troops opposing them and forced them to retreat. Legio XXII and the Galatians in the center and Legio XXXVI on the left were hard-pressed, but another hour's fighting threw back the remainder of the Pontic forces, retreating in complete disorder. The Pontic army ran back to its fortified camp, but did not stop. The victorious Romans followed the routing enemy, and quickly captured the Pontic encampment after a sharp fight with the units guarding


Roman casualties are not mentioned. Pontic losses were described thus: "Almost the whole army was cut to pieces or made prisoner." Pharnaces escaped the carnage of his army with a small cavalry escort.

Footnote #1: Pharnaces fled back to the Bosporan Kingdom, 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. His former governor and son-in-law attacked his forces and killed him. The historian Appian states that Pharnaces died in battle, while Cassius Dio says he was captured and then executed.

Footnote #2: On his return trip to Rome, Caesar wrote a report about the battle for the Senate. It contained three Latin words: "Veni, vidi, vici." [The proper Latin pronunciation of the phrase is: WEE-knee, WEE-dee, WEE-key.] "I came, I saw, I conquered." This phrase has come down to us as the synopsis of Caesar's entire career.

Footnote #3: Shortly after the conclusion of this battle, Caesar returned to Rome after he received reports that his lieutenant Mark Antony was not managing affairs very well. Four veteran legions threatened to mutiny if they were not paid – still in arrears since the conquest of Gaul in 58-52 – and received their discharges. Caesar arrived in Rome in August, quelled the mutiny, and enlisted the four legions into his upcoming North African and Hispanian campaigns.

Footnote #4: On January 1, 45 BC, the old Roman calendar was abolished, replaced by a new one developed by Caesar. The Roman calendar was then regulated by the movement of the moon, and this had left it in a mess. Caesar replaced this calendar with the Egyptian calendar, which was regulated by the sun. He set the length of the year to 365.25 days by adding an intercalary/leap day at the end of February every fourth year. To bring the calendar into alignment with the seasons, he decreed that three extra months be inserted into 46 BC (the ordinary intercalary month at the end of February, and two extra months after November). Thus the year 46 BC consisted of 445 days.

Footnote #5: Shortly before his assassination, Caesar was proclaimed dictator for life. Only after this act did the plot to eliminate him truly coalesce. Less than three years after his great victory at Zela, Julius Caesar was struck down while the Senate was in session. He was stabbed 23 times. [The Senate ordered that Caesar's body be examined, which is credited with being the first recorded autopsy.]

"Murder of Caesar" by Karl von Piloty (1867); oil on canvas; Currently located in the Lower Saxony State Museum, Hanover, Germany
"Murder of Caesar" by Karl von Piloty (1867); oil on canvas
Currently located in the Lower Saxony State Museum, Hanover, Germany

Posted in top stories | 0 comments
« Previous story
Next story »


* To comment without a Facebook account, please scroll to the bottom.

Add new comment

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Have a tip for us? A link that should appear here? Contact us.
News from the World of Military and Veterans Issues. Iraq and A-Stan in parenthesis reflects that the author is currently deployed to that theater.