Siege of Alexandria, August 48-January 47 BC

The siege of Alexandria (August 48 BC-January/ February 47 BC) saw Julius Caesar become trapped in the city after getting involved in Egyptian politics. He was only able to escape after a relief army reached the city, allowing him to defeat Ptolemy XIII and his allies at the battle of the Nile (Great Roman Civil War).

In the aftermath of his defeat at the battle of Pharsalus, Pompey the Great, the defeated Republican commander, attempted to find a safe refuge somewhere in the east. Greece and the surrounding areas soon became too dangerous, especially after Caesar decided to put all of his efforts into catching Pompey. The people of Antioch made it clear that Pompey wouldn’t be welcome there. Pompey then decided to go to Egypt, where he hoped to gain support from the young Ptolemy XIII. Pompey had supported Ptolemy’s father Ptolemy XII Auletes, and many members of the king’s army had previously served under Pompey. Ptolemy was also engaged in a civil war with his sister Cleopatra VII Philopater. However some of the young king’s advisors worried that Pompey would be able to subvert their army, and had him assassinated when he landed on the shore near Pelusium.

Battles of the Great Roman Civil War, 49-45 BC
Battles of the
Great Roman Civil War,
49-45 BC

Caesar arrived at Alexandria a few days after Pompey’s death. He was accompanied by 3,200 men from two under-strength legions, 800 cavalry, ten warships from Rhodes and a few others from Asia, but he was confident that his fearsome reputation would keep him safe. This would soon prove to have been a dangerous gamble. He learnt of Pompey’s death soon after arriving in Egypt, and according to Plutarch shed tears when he was presented with Pompey’s seal ring and recoiled in horror when he was shown his head. Pompey might have been his enemy, but he was also a senior Roman, and his death at Egyptian hands an unacceptable blow.

We have a number of sources for the events in Egypt. For the period between Ceasar’s arrival at Alexandria and the outbreak of fighting we might have Caesar’s own words, in the last section of his Civil War.  This breaks off early in the siege, and is replaced by the Alexandrian Wars, presented as a continuation of the Civil War, but probably not written by Caesar. The Alexandrian Wars may have been written by Caesar’s friend and ally Aulus Hirtius. Plutarch’s life of Caesar includes some details, and there is a brief summary in Appian.

According to Caesar’s Civil War, when he arrived at Alexandria the city was in turmoil. He found himself trapped there by the etesian winds, blowing strongly from the north, and so decided to summon other legions to come to his aid in Egypt, but it would take some time for them to arrive. He decided that the dispute between Ptolemy and Cleopatra was of direct concern to the Roman people, while he was directly involved because an alliance had been formed between Ptolemy XII and Rome during Caesar’s first spell as consul. As a result he ordered Ptolemy and Cleopatra to disband their armies and settle their dispute legally, with Caesar as the judge. In the meantime Caesar moved into the Royal palace.

Ptolemy’s government was run by the eunuch Pothinus, who had played a major role in the death of Pompey. He now began to plot against Caesar. Caesar and Plutarch have slightly different versions of these events.

According to Plutarch Pothinus goaded Caesar with fairly petty acts - providing poor grain for his troops or using wooden and earthenware dishes at meals, and suggesting that he should leave Egypt and return to his own affairs. Caesar rebuffed him, and decided to summon Cleopatra to the palace. In order to get past Ptolemy’s guides, she had to be hidden in a carpet or a bed sack and carried into the palace, a daring move that helped win Caesar to her side. Caesar forced the two to make a public reconciliation, but at this point one of his servants uncovered a plot involving Pothinus and Achillas, one of Pompey’s assassins. Caesar captured and executed Pothinus, but Achillas escaped and brought the Royal army to Alexandria to attack Caesar.

In Caesar’s account, Pothinus summoned the Royal army from Pelusium, and placed Achillas in command. When the Royal army approached the city, Caesar got Ptolemy to send envoys to find out what Achillas intended, but they were attacked and one was killed when they entered the camp. Caesar took possession of Ptolemy, and decided to defend part of the city. Achillas had around 20,000 men, including a number of former Roman soldiers who had served under Gabinius, and then entered Egyptian service. Caesar was thus badly outnumbered.

The siege began with a general assault by Achillas. Part of his army was sent to attack Caesar’s residence while a larger part was sent to try and seize the port area, and in particular the 72 warships that were present there. Caesar realised that he couldn’t hope to protect the entire harbour area with his small forces, and so had the ships burnt. He was also able to fight off the attack on his residence, and send a force to occupy Pharos island, dominated by the famous light house. Possession of Pharos meant that Caesar controlled access to the harbour, but later events show that he wasn't able to hold onto it at this time.

Caesar began to fortify his part of the city. His area was centred on part of the palace and a nearby theatre, which he turned into a citadel. He had access to the port, and was given the time to fortify the area. He lost control of Cleopatra’s sister Arsinoe, who escaped from the palace and joined Achillas, but then attempted to seize control of his army, dividing Caesar’s opponents. This is the point at which Caesar reports the death of Pothinus, executed after it was discovered that he was sending messengers to Achillas. This is the point at which Caesar’s work ends, and we move onto the Alexandrian Wars.

Both sides concentrated on fortifying their part of the city. Caesar occupied the smaller part of the city, bordered to the south by a morass that provided him with water and forage. The Alexandrians built a forty foot high triple wall to defend their part of the city, dotting it with ten story towers and building a number of mobile towers that could be moved to any danger zone.

The division in the Alexandrian army soon came to an end, after Arsinoe had Achillas killed. She then placed her governor Ganymed in command of the army. His first plan was to try and cut off the supply of fresh water to the Roman held area, first by cutting the canals that brought fresh water into the city’s cisterns, and then by pumping sea water into the canals in Caesar’s area. The drinking water available to the Romans gradually turned brackish. This caused a brief crisis of morale in Caesar’s forces, but he was able to reassure them, and they were soon able to dig wells that produced enough fresh water.

Soon after this the first Roman reinforcements arrived in the area. This was the 37th Legion, formed by Caesar using some of Pompey’s veterans. An easterly wind stopped the legion from entering the city, but they were able to ride at anchor just off the coast near the city, and sent messages into the city to let Caesar know they had arrived.

Caesar decided to take his small fleet out to sea to meet with his reinforcements, but he decided not to embark any soldiers onboard, as he didn’t want to weaken the defences of his enclave. This almost led to disaster. Caesar’s fleet reached Chersonesus, and sent some of his sailors inland to fetch water. Some of them went too far and were captured by the Alexandrians, who thus discovered that Caesar was actually present with the fleet, and had no soldiers with him. They decided to try and intercept Caesar on his way back to the city. Caesar decided not to risk a battle, and instead headed towards the shore, but one of his Rhodian galleys became isolated on his right wing, and was attacked by a series of four decked warships. Caesar had to come to its assistance, and came close to winning a major naval victory before night ended the fighting. Even so his men captured one four banked galley, sank a second and disabled a third. He was then able to tow the stranded transport ships into Alexandria. 

The Alexandrians then decided to equip a new fleet. They gathered in all of the ships stationed at the mouths of the Nile to collect customs, and the older warships in the king’s arsenals. They were able to find 22 quadriremes and 5 quinqueremes, along with a large number of smaller ships. They then prepared for a second naval battle.

Caesar now had nine Rhodian galleys, eight from Pontus, five from Lycia and twelve from Asia, including ten quadriremes and five quinqueremes. He thus had 34 major warships compared to 27 on the Alexandrian side, but on average his ships were smaller.

The two fleets formed up on opposite sides of an area of shallow water towards the western side of the city (off the part of the city said to be in the African coast). Caesar placed his Rhodians galleys, under Euphranor, on his right and his Pontian galleys on his left. He left a gap between the two wings, and posted the rest of his ships in the rear as a reserve. The Alexandrians placed their 22 quadriremes in the front row with the rest of their fleet in the rear. Both sides then waited for the other to make the first move, with neither wanting to fight with the shallows behind them.

Eventually Euphranor volunteered to lead his ships through the shallows, and hold off the Alexandrians while the rest of the fleet got through. The battle began after the first four Rhodian ships were through. The Alexandrians were unable to close with them, and the rest of the fleet soon came to their aid. The battle then turned into a naval melee, which ended as a minor Roman victory. One quinquereme and one bireme were captured and three biremes sunk before the rest of the Alexandrian fleet took shelter under the mole (presumably the mole leading to the lighthouse)

Caesar’s next plan was to seize the Pharos island, and thus gain control of the harbour. He chose ten cohorts, supported by light infantry and the best of the Gallic cavalry, and led them across to the island on small boats, while his fleet caused a distraction by attacking the island elsewhere. At first the defenders of the island held the Romans at the shore, but they were soon forced to retreat into the town on Pharos Island. Caesar was able to take one of the two castles on the island, but his attempt to take the second castle failed after the Alexandrians attacked the mole and the Roman positions on the bridge that connected the island to the mainland. Eventually Caesar’s men were overwhelmed and began to retreat. Caesar was forced to move back to his galley, but this was sunk by the weight of fleeing troops who attempted to escape on her. Caesar himself was forced to swim to safety. The Alexandrians then took secure possession of the Pharos island, and gained control of the harbour.

After this setback the Alexandrians asked Caesar to allow Ptolemy to join the Egyptian army, so he could overthrow Arsinoe and Ganymed, and form an alliance with Caesar. Caesar didn’t hold out much hope that Ptolemy would keep his word, but decided to risk releasing him anyway. Much as Caesar had expected, Ptolemy soon took control of the war against him.

By now the Alexandrians were becoming demoralised. Their young king wasn’t an inspiring leader, and news had reached them that Roman reinforcements were on their way from Syria. The Alexandrians decided to try and intercept the supply convoys that were still reaching Caesar, and dispatched their fleet to guard the Canopic mouth of the Nile. Caesar sent his own fleet, under Tiberius Nero, to try and prevent this. A small battle developed at Canopus, in which Caesar’s successful Rhodian admiral Euphranor was killed.

By now the relief army was closing in. This force was led by Mithridates of Pergamum, a loyal ally of Caesar, and was made up of troops from Syria and Cilicia. Achillas had attempted to block them at Pelusium before his fall, but Mithridates seized that fortress in a single day and marched across Egypt. Ptolemy attempted to intercept him before he could reach Caesar, but his first attacks failed. He then left Alexandria to take command of the next attack in person, while Caesar rushed to aid his ally. The resulting battle of the Nile ended as a clear Roman victory.

Ptolemy was drowned while attempting to escape from the scene, leaving Caesar in undisputed control of Egypt. He placed Cleopatra on the throne, alongside her younger brother Ptolemy XIV. Caesar then spent some time in Egypt, enjoying the company of Cleopatra, and possibly taking part in a cruise up the Nile. Soon after Caesar’s departure, Cleopatra gave birth to a son, who she named Caesarion, making it clear just who she believed his father to be.

Caesar’s Egyptian interlude was almost disastrous for his cause. While he was trapped in Egypt, his Republican opponents were able to raise another vast army in Africa, while Mark Antony’s rule alienated many in Italy. Elsewhere Pharnaces, son of Mithridates of Pontus, defeated a Roman army at Nicopolis, threatening the settlement of the east. Once Caesar was freed from his Egyptian entanglement he quickly restored the situation. First he defeated Pharnaces at Zela, and then he defeated the Republicans at Thapsus, ended the last serious opposition to his rule.

How to cite this article: Rickard, J (24 August 201), Siege of Alexandria, August 48-January 47 BC ,

Help - F.A.Q. - Contact Us - Search - Recent - About Us -  Subscribe in a reader - Join our Google Group - Cookies