Memnon of Rhodes (d.334) was one of the few successful Persian commanders during the wars against Philip II of Macedon and Alexander the Great, despite have started his military career as a rebel against Artaxerxes III.
Memnon was the son of Timocrates of Rhodes, a Greek who had worked for the Persians in the 390s and helped trigger the Corinthian War , in order to distract the Spartans from their ongoing campaign in Asia Minor.
Memnon first comes to our attention during the Satrap's Revolt of the 350s. His brother Mentor was a senior military commander under the rebel satrap Artabazus of Phrygia while their sister was married to the satrap. By around 354 BC the Persians had reoccupied Phrygia, and the brothers were forced to flee into exile. Mentor went to Egypt, where he entered the service of Nectanebo II of Egypt. Memnon fled to Macedon.
In 346/5 Mentor betrayed the port of Sidon to the Persians. After his capture he was pardoned and entered Persian service, where he played a major role in the Persian conquest of Egypt of 343 BC. As a reward he became commander-in-chief of the Western Satrapies, and was able to get his brother Memnon pardoned. Memnon then entered Persian service.
In 340 Mentor died. Memnon didn’t inherit his post as commander-in-chief in the west, but he was appointed as commander in the Troad, in the north-west of Asia Minor. This province was on the Asian side of the Hellespont, and meant that Memnon was in the front line when the Macedonians began to threaten the Persian Empire. Memnon kept his post during the short reign of Artaxerxes IV and into the reign of Darius III, the final Persian emperor.
In 336 Philip II sent 10,000 men under one of his most trusted generals, Parmenion, to invade Asia Minor and create a bridgehead for the main Macedonian invasion. Permenion quickly conquered large parts of western Asia Minor, reaching as far south as Ephesus. Darius responded by giving Memnon enough money to hire 5,000 mercenaries. He then intercepted the Macedonians at Magnesia, near the Meander River, and inflicted a defeat on them. Parmenion retreated back to Abydus on the Asian side of the Hellespont to defend the Macedonian bridgehead.
Next Memnon attempted to lift the Macedonian sieges of Gryneion and Pitane, in Aeolia on the western coast of Asia Minor. He saved Pitane, but Gryneion fell. He then moved north and tried to win over the important independent trading city of Cyzicus, located on an island on the southern side of the Sea of Marmora. These efforts failed, but he had more luck in battle against Parmenion's replacement Calas, defeating him in a battle in northern Anatolia. Calas retreated to the Greek city of Rhoeteum in the Troad. Memnon might have completed the campaign of 335 by retaking Ephesus.
The situation changed dramatically in 334 BC. Philip had been assassinated late in 336 and succeeded by his son Alexander. Alexander needed 335 to secure his authority in Greece and Macedonia, but by 334 he was ready to resume his father's invasion of the Persian Empire. Early in the spring Alexander crossed the Hellespont. His early arrival meant that Memnon's original plan, which was based on gathering in the harvest and storing it in the most defensive cities and starving the Macedonians out, had to be abandoned. Memnon and the local Persian satraps held a meeting soon after Alexander's. Memnon advocated a scorched earth strategy, but he was overruled. The satraps insisted on seeking out battle, hoping to defeat the Macedonian invasion before it could truly get underway.
Memnon and the satraps assembled quite a sizable army, and advanced to the River Granicus, where they could block Alexander's planned advance on the important city of Dascylium. The resulting battle of the Granicus (May 334 BC) was the first of Alexander's major battlefield victories over the Persians. Memnon fought in the battle, commanding a force of cavalry. Memnon and the entire Persian cavalry force fled from the scene after Alexander broke through the Persian line. Memnon performed bravely in the battle, and in its aftermath was appointed as commander of all Persian forces in southern Asia Minor.
His next task was to try and defend the key naval base at Halicarnassus. He strengthened the defences, made sure that there was plenty of food in the city, and prepared for a lengthy siege. Alexander was held up for some time outside the city, but after the failure of a sortie aimed at the Macedonian rams and catapults Memnon decided that the city couldn't be held. He withdrew most of his force to Kos, leaving a Persian garrison to protect the harbour defences. Alexander took the city, but the harbour was blocked until 332 BC.
The last phase of Memnon's career was the most dangerous for Alexander. He decided to move west into the Aegean, to threaten Greece and Alexander's links home. It was also possible that he could stir up anti-Macedonian revolts in Greece. He had 300 ships and 10,000 mercenaries for this campaign.
Memnon began by bribing the leaders of Chios to change sides. He then moved to Lesbos, where he was able to capture Pyhrra, Arissa and Methymna. However the key city of Mytilene held out, and Memnon was forced to besiege it. Alexander was forced to react to these successes by summoning a number of fleets to defend key points around the Aegean, but the danger was averted by the death of Memnon during the siege. He died of illness at some point in May-June, well before the surrender of Mytilene in August 333. With his death the drive went out of the Persian campaign in the Aegean. Darius withdrew the mercenaries from the fleet, which withdrew to Kos.