The Siege of Alexandria was a series of skirmishes and battles involving the armies of Julius Caesar and his lover Cleopatra against the armies of her brother Ptolemy XIII, backed by the Order of the Ancients in 47 BCE.
After Pompey's armies were defeated by Caesar's forces in their own civil war, his armies were scattered or surrendered to Caesar. Pompey, however, escaped death. While at sea off the Aegean coast his ship was boarded by Aya of Alexandria to discuss an alliance with Cleopatra, after agreeing he sailed straight for Egypt. He was later killed upon landing in Egypt by Lucius Septimius, a former soldier in his army. The assassination was proposed by the eunuch Pothinus, advisor to the pharaoh Ptolemy XIII who deemed that Caesar would be pleased by the removal of his adversary. This turned out to be a bad decision, as Caesar was angered by the death of his rival, prompting him to later side with Cleopatra. Pothinus and Ptolemy were unhappy with this turn of events.
He ordered his men to dig a ditch around the palace and build a wall leading to the harbor. This would ensure Caesar's access to the sea. When the Egyptian general Achillas arrived in the city with 20,000 men, the battle for Alexandria began.
With so few men at his disposal, Caesar could not risk a battle so soon. He sent ambassadors to Achillas, in the name of Ptolemy, to propose a truce. Knowing that the orders did not come from the young king and angered by the pharaoh's imprisonment, Achillas had the messengers assassinated.
With Caesar confined within the palace, Achillas positioned his troops around the city. Skirmishes broke out through the streets of Alexandria, and went on for several days and nights. Though they were outnumbered, Caesar's men were able to hold the enemy back. This prompted Achillas' next move: capture the Roman fleet stationed in the harbor.
Although the palace offered protection, losing the port meant the end of help and supplies. Caesar knew he had to protect the fleet. While he and his troops succeeded in regaining control of the port, he knew it would be impossible to sustain. Caesar ordered the burning of the ships. With passage to the palace closed off, he headed for the Lighthouse of Alexandria.
Fighting their way through the Egyptian troops, Caesar and his men eventually reached Pharos island. There they took refuge within the lighthouse. With easy access to the open sea, Caesar was able to send messages to his allies requesting reinforcements and more supplies. The island fort also allowed him to control access to the harbor by relying on the chains used by the Egyptians to control ship traffic to and from Alexandria's docks.
Egyptian soldiers poured salt water into the aqueducts supplying Alexandria, trying to force Caesar and his men out. Panic erupted within Caesar's men. They wouldn't last long without fresh water. Recognizing that the porous limestone could help them, Caesar and his men dug wells to help restore their water supply. Days later, the 37th Legion, comprised of Pompey's soldiers, arrived by ship. Unable to come ashore due to the winds, Caesar risked going out to meet them on the peninsula, Cape Chersonese. When the enemy learned of Caesar's location, they rushed to intercept.
Despite an obvious advantage for the Alexandrians, Caesar, with a Rhondian ship full of skillful sailors, emerged victorious. With help from the allied ships, Caear's victory enabled him to push the Egyptians back and secure the lighthouse. Gaining control of Pharos island sent the Alexandrians into the sea and swimming back to the city. However, Caesar's fortification of the island didn't last long. The enemy regrouped and were set to storm the island. Panic-stricken, in spite of Caesar's encouragement, many of his men then fled their posts either by ship or jumping into the sea.
Caesar attempted to retreat, but Port Eunostos' harbor was overrun with enemy ships preventing escape. He managed to swim to safety to an allied ship farther out, although he had to remove his purple garment else he would have drowned. The Alexandrians recovered the garment and paraded it as a trophy to commemorate the Roman debacle.
The Alexandrians wanting their king back decided to approach Caesar with a compromise. Caesar agreed to release Ptolemy XIII, after entreating him to spare the kingdom and remain loyal to Rome. Once freed, however, the king defied the agreement and continued to war.
Caesar sent the Hidden One Aya to deal with Ptolemy who was trying to flee via the Nile Delta. During the Battle of the Nile Aya decided to spare Ptolemy, although a few moments later his boat attacked by crocodiles and he drowned in the Nile.
After the siege ended, Cleopatra reigned over Egypt until 30 BCE. Under her rule, Alexandria settled into its position within the Roman Empire, and eventually surpassed Athens as one of the most important cities in the Roman Empire. Julius Caesar remained in Egypt for a short time. He and Cleopatra would later have a son, named Caesarion.