Forgotten Empire: The World of Ancient Persia, eds. John Curtis and Nigel Tallis. Berkeley Los Angeles: University of California Press, 2005.
**The following material is my summary of context on pages 13-16 of the above cited work.
The king who ruled after the golden period (see last post) was the famous king Xerxes (486-465 BC). Perhaps he is more famous for the defeats he suffered in the second Persian War (480-479 BC) than for anything positive (e.g. the action movie 300). In spite of the creation of the Delian League in 478 BC under the control of Athens that seriously threatened Persian control in the eastern Aegean, the Achaemenid Empire did not enter into a long period of decline during Xerxes reign. Such is a Greek-centered view of the Persian Empire, and does not bear up to analysis of Elamite documentation from Persepolis.
It is true, however, that the Persian Empire was not a monarchy of the constitutional type where the ultimate word lies with a stable body of decision makers rather than the standing army. Because of this, “the dynastic succession was very frequently called into question by plots and assassinations.” Xerxes was assassinated by plotters and his death was followed by a violent dispute among his sons. Although his successor, king Artaxerxes (465-424 BC) was not assassinated and enjoyed a long reign, his successor Darius II (424-404 BC) gained power by force after his death in a similar situation. Likewise, Darius’ successor, Artaxerxes II (404-358 BC) had to defend his claim to power against Cyrus the Younger who raised an army including soldiers from as far as Greece and advanced as far as Babylonia in hopes to seize power. Because the Persian king was king over lands that extended so far, rebellions were inevitable—especially once the Delian League mustered alliance insecurities around Mediterranean Sea. Unfortunate for Cyrus, Artaxerxes II defeated him at the battle of Cunaxa and enjoyed the longest reign of any Achaemenid king—forty-six years in total. See Tomb of Artaxerxes II below (picture not from book).
One of the consequences of this civil war was the loss of Persian control in Egypt. Between 404 and 400, Egypt was able to pose a threat to Persian control. At the end of this period, control in Egypt had been successfully seized by an Egyptian dynasty. Although Artaxerxes II was unable to give his full attention to Egypt at the time and lost control, this was the greatest loss for the duration of his power. He is also responsible for stamping out the so-called “great revolt of the satraps,” the most serious incident occurring between 366 and 359 BC in the western coastal areas. Satraps were provincial governors of the Persian Empire, so this was a united rebellion of certain western parts of the empire. The uprising ended pitifully according to the Greek author Diodorus of Sicily. Orontes, their leader, found it more convenient to deliver his companions to the royal government. The central government of the Achaemenid dynasty was never seriously threatened by the rebellion of the satraps.