During the second invasion, Artaxerxes finally defeated Nectanebo II, the Pharaoh of Egypt, bringing the country back into the Persian fold after six decades.

In Artaxerxes' later years, Philip II of Macedon's power was increasing in Greece, where he tried to convince the Greeks to revolt against the Achaemenid Empire.

There is evidence for a renewed building policy at Persepolis in his later life, where Artaxerxes erected a new palace and built his own tomb, and began long-term projects such as the Unfinished Gate.

[9] A eunuch discovered the conspiracy, and as a result Darius was summoned to the court and executed, "along with the wives and children of all the conspirators" (Justin).

However, Ochus, with the support of some eunuchs,[a] created a series of ruses and allegations to make his legitimate brother Ariaspes go mad and commit suicide.

[8][11] At his accession (which happened sometime between November 359 and March 358 BC),[12] Artaxerxes III demanded that all the satraps in western Anatolia were to disband their mercenary forces.

Later in 356 BC, Artaxerxes III attempted to dismiss Artabazus II from his satrapy of Hellespontine Phrygia, which resulted in the latter revolting.

[14] Artabazus quickly joined forces with the Athenian military commander Chares, who had acquired most of his disbanded mercenary unit.

After a year of fighting the Egyptian Pharaoh, Nectanebo inflicted a crushing defeat on the Persians with the support of mercenaries led by the Greek generals: the Athenian Diophantus and the Spartan Lamius.

[25] Both satraps suffered crushing defeats at the hands of Tennes, the Sidonese king, who was aided by 4,000 Greek mercenaries sent to him by Nectanebo II and commanded by Mentor of Rhodes.

[24] Artaxerxes sold the ruins at a high price to speculators, who calculated on reimbursing themselves by the treasures which they hoped to dig out from among the ashes.

[32] Although the Artaxerxes's army considerably outnumbered that of his Egyptian counterpart Nectanebo II, the difficulty of marching through the dry land south of Gaza and the many rivers of Lower Egypt still posed, as in previous invasions, a challenge, which was compounded, according to Diodorus Siculus, by the refusal of the Persians to make use of local guides.

One unit, to which he assigned the Thebans, a force of cavalry and Asiatic infantry, was tasked with taking Pelusium, while a second, commanded by Mentor of Rhodes and the eunuch Bagoas, was sent against Bubastis.

The third division, which comprised the Argives, some unspecified elite troops and 80 triremes, was to establish a bridgehead on the opposite bank of the Nile.

[33][35] After an attempt to dislodge the Argives failed, Nectanebo retreated to Memphis, which prompted the besieged garrison of Pelusium to surrender.

This was followed by a wave of surrenders, which opened the Nile to Artaxerxes's fleet and caused Nectanebo to lose heart and abandon his country.

[33][36] After this victory over the Egyptians, Artaxerxes had the city walls destroyed, started a reign of terror, and set about looting all the temples.

Mentor, who was governor of the entire Asiatic seaboard, was successful in reducing to subjection many of the chiefs who during the recent troubles had rebelled against Persian rule.

[24] The Persian forces in Ionia and Lycia regained control of the Aegean and the Mediterranean Sea and took over much of Athens’ former island empire.

[24] By the last year of Artaxerxes' rule, Philip II already had plans in place for an invasion of the Persian Empire, which would crown his career, but the Greeks would not unite with him.

[39] In late August/late September 338 BC, the court eunuch and chiliarch (hazahrapatish) Bagoas orchestrated the poisoning and subsequent death of Artaxerxes III through the latter's own physician.

[45] Mithra and Anahita had until then been neglected by true Zoroastrians—they defied Zoroaster's command that God was to be represented only by the flames of a sacred fire.

Strangely, Artaxerxes had ordered that statues of the goddess Anâhita be erected at Babylon, Damascus and Sardis, as well as at Susa, Ecbatana and Persepolis.

[20] In 341 BC, after Artaxerxes returned to Babylon from Egypt, he apparently proceeded to build a great Apadana whose description is present in the works of Diodorus Siculus.