Cambyses II
Cambyses II, was the second king of the Medo‑Persian Empire, succeeding his father Cyrus II "The Great". He reigned from 530 BC until his death in 522 BC and presided over the first major expansion of the Achaemenid Empire into Africa. Cambyses is remembered for his conquest of Egypt, the mysterious disappearance of his army in the western desert, and the political turmoil that followed his death.
Mental Health
Ancient sources give conflicting accounts of Cambyses’ mental stability. Herodotus portrays him as increasingly erratic, attributing episodes of cruelty and impulsive violence to a deteriorating mental state. Modern historians debate the accuracy of these claims, noting that Herodotus wrote from a Greek perspective hostile to Persia, but it is historically appropriate to summarize the traditional view that Cambyses’ behavior became unstable during his Egyptian campaign.
Murder of Smerdis
Before departing for his Egyptian campaign, Cambyses II secretly ordered the assassination of his brother Smerdis (Bardiya). According to Herodotus, Cambyses feared that Smerdis’ popularity and royal lineage might enable him to challenge the throne during Cambyses’ absence. He therefore instructed his trusted courtier Prexaspes to kill Smerdis quietly and without public knowledge. The murder was concealed from the Persian people and even from most of the nobility.
This secrecy later produced a major crisis. While Cambyses was in Egypt, a Magian named Gaumata impersonated Smerdis and proclaimed himself king. Because the real Smerdis had been killed in secret, the impersonation was widely believed, and the Persian administration accepted Gaumata as the legitimate monarch. When Cambyses learned that “Smerdis” had seized the throne, he immediately attempted to return to Persia to expose the impostor. He died on the journey in 522 BC, leaving the False Smerdis temporarily in control of the empire.
The deception was eventually uncovered by Darius I, who led a group of conspirators to overthrow and kill Gaumata. Thus, Cambyses’ decision to murder Smerdis — and to hide the act — directly enabled the Magian Revolt and shaped the succession of the Achaemenid Empire.
Campaign of Egypt
Cambyses II launched the Persian invasion of Egypt in 525 BC, completing the Achaemenid expansion begun under his father, Cyrus the Great. The decisive engagement was the Battle of Pelusium, where Persian forces under Cambyses defeated Pharaoh Psamtik III and opened the Nile Delta to Persian occupation. After the victory, Cambyses entered Memphis and was recognized as Pharaoh, incorporating Egypt into the Achaemenid imperial system.
The campaign combined conventional military operations with political and psychological measures. Ancient authors report that Cambyses used both naval and land forces, secured alliances with local tribes, and exploited divisions within Egypt’s ruling elite. After the conquest, he installed Persian administrators and garrisoned key cities to secure the new province.
Cambyses’ Egyptian campaign is also notable for his visit to the Oracle of Ammon at Siwa, a journey that later authors treated as a significant personal and religious episode. The expedition to Siwa and the events surrounding it figure prominently in the ancient narratives of Cambyses’ reign.
The Lost Army
One of the most famous and debated episodes of Cambyses’ Egyptian campaign is the disappearance of a large Persian force sent toward the Siwa Oasis. The principal ancient account is Herodotus, who reports that Cambyses dispatched an army—often given as 50,000 men in the tradition—to destroy the oracle at Siwa after the priests there refused to acknowledge him. According to Herodotus, the force was overwhelmed by a sudden sandstorm and perished in the desert; the survivors were never heard from again.
Diodorus Siculus and later compilers repeat the story in broadly similar terms, though details and numbers vary. Modern scholars treat the episode with caution: while the scale and some particulars in Herodotus’ narrative are likely exaggerated, archaeological and geographical studies confirm that the western desert routes to Siwa are hazardous and that large detachments could be lost to storms, lack of water, or logistical failure.
Note:
- Herodotus’ account mixes fact and moralizing narrative. He uses the lost army story to illustrate themes of hubris and divine retribution; therefore, his numbers and some dramatic details should be presented as part of the ancient tradition rather than as incontrovertible fact.
Death
Upon learning that False Smerdis had seized the throne, legend records that he jumped upon his horse and thereby accidentally cut his thigh with his sword and contracted gangrene, from which he later died.