Artaxerxes III (r.359-338 BC) was the third-from-last Persian emperor of the Achaemenid dynasty, and restored Persian control of Egypt after just over sixty years of independence. Before he came to the throne he was called Ochus, but he took his father's name after becoming Emperor.
Artaxerxes III succeeded his father Artaxerxes II to the throne in 359 BC. In the aftermath of his succession he killed off many of his close relatives in an attempt to prevent revolts again him, leaving the Achaemenid family rather short on male heirs. In 356, in a further attempt to secure his position, he ordered the satraps to dismiss all of their mercenary troops.
Although the later Persian Empire wasn't as powerful as it had been under the earlier emperors, Artaxerxes III was still able to intervene effectively in Greece. The Social War of 357-55 BC, which saw Athens attempting to punish some of her allies, was a breach of the King's Peace of 387-6, which had guaranteed the autonomy of most Greek cities. Artaxerxes was able to force Athens to accept a peace in which some of their allies were granted autonomy.
Egypt had revolted against the Persians in 405 BC, and had fought off a Persian attack in 373. Artaxerxes made a first attempt to reconquer Egypt in 351-350, but without success. Few details of this campaign have survived, but it was mentioned by Demosthenes in his On the Liberty of the Rhodians of 351 as an ongoing campaign that was rumoured to have failed.
This failure possibly helped to trigger a revolt that began in Sidon, and spread to Palestine, Phoenicia and Cilicia. The revolt was crushed in 345, when Artaxerxes, aided by Mentor of Rhodes, led a massive army against Sidon.
In 343 Artaxerxes III raised an army with Greek contingents from Thebes, the Argive and Asia Minor and led that army in person on yet another campaign in Egypt (although the eunuch Bagoas served as commander-in-chief of the army). This time he was successful, and Persian control was restored after a great victory at Pelusium. He did fail to capture the defeated royal family and the pharaoh Nectanebo II, who fled south into Nubia. Artaxerxes had the walls of Egyptian cities destroyed, plundered their temples, and was said to have personally killed the sacred Apis Bull. Although Persian rule had been re-established, these actions made it very unpopular, and help explain why Alexander the Great was greeted so readily when he invaded.
Artaxerxes's biggest foreign policy mistake was underestimating the threat from Philip II of Macedonia. He refused to support Athens against the Macedonians. In 340 Philip besieged Perinthus and Byzantium, on the European side of the Bosphorus. Artaxerxes sent help to the cities, and forced the Macedonians to lift the siege. This was only a temporary setback for Philip, who went on to win dominance of Greece at Chaeronea (338 BC), at the end of the Fourth Sacred War. Most of mainland Greece was now under Macedonia control, denying the Persians the chance to play off different Greek factions against each other as they had done so successfully in the past.
In 338 Artaxerxes was poisoned by his doctor, who was following the orders of the eunuch Bagoas. All but one of his sons were also murdered at this time. Bagoas then placed the surviving son, Arses, on the throne (338-336), before finally helping raise Darius III, the last Achaemenid emperor, to power.
Although Artaxerxes's reign was marked by the last significant Persian successes, he had a very bad press in the ancient sources, being described as reckless, a coward, secluded in his palace, a merciless despot and his successes were credited to either Greek mercenaries or the poor qualities of his opponents. However he must have had more qualities than he is normally given credit for, as he was able re-conquer Egypt and still had significant influence in Greece.