Memnon of Rhodes

[close] was the commander of the Greek mercenaries in the service of the Persian king Darius III when Alexander the Great of Macedonia invaded Persia in 334 BC. Memnon famously advocated a scorched earth policy against Alexander, aware of the Macedonian's lack of supplies and funds. He commanded the mercenaries at the Battle of the Granicus River, where his troops were massacred by the victorious Macedonians.
He then began a campaign to capture the Aegean islands using the Persian fleet and led a direct assault on Macedonia, while Alexander was resting at Phaselis. Memnon managed to capture the island of Chios and most of Lesbos. Demosthenes, after hearing of Memnon's successes, began to prepare Athens for a revolt against Alexander, along with other Greek cities, while Sparta began to prepare for war. By a stroke of fortune for Alexander, Memnon died of illness at Mytilene after transferring command to his nephew, Pharnabazus.

Many scholars maintain that had Memnon's campaign been successful, Alexander would have had difficulty in continuing his campaign in Asia, and might have soon been defeated. It was not until after the major Persian defeat at the Battle of Issus that Memnon's strategy was revitalised and finally put into action, but by then the advantage had been lost, and Alexander showed himself willing to forfeit Greece if necessary in favor of his greater goals.
Memnon was the brother of Mentor of Rhodes, brother-in-law of Artabazus of Phrygia, and husband and uncle of Barsine, Artabazus' daughter and Alexander the Great's mistress.