Darius III (Darius Codomannus) (kŏdəmăn´əs), d. 330 BC, king of ancient Persia (336–330 BC). A cousin of Artaxerxes III, he was raised to the throne by the eunuch Bagoas, who had murdered both Artaxerxes and his son, Arses; Darius in turn murdered Bagoas. His rule was not stable, however. When Alexander the Great invaded Persia, Darius was defeated in the battle of Issus (333 BC) and again in the battle of Gaugamela near Arbela (331 BC). For the first time Persia was confronted by a united Greece, and Darius' greatest error was in underestimating Alexander's strength. Darius used the wrong tactics in battle and was forced to flee to Ecbatana and then eastward to Bactria. It was there that the satrap of Bactria, Bessus, had Darius murdered on Alexander's approach and took command himself in the unsuccessful opposition to the Macedonian conqueror. These events brought the Persian Empire to an end and marked the beginning of the Hellenistic period in the E Mediterranean. Darius III is probably the Darius the Persian mentioned in the Bible (Neh. 12.22).