Cambyses II (r.529-522 BC) was the second Achaemenid Emperor of Persia, succeeding his father and founder of the Empire, Cyrus II the Great. His most notable achievement was the conquest of Egypt, but he died under mysterious circumstances while rushing home to deal with a revolt against his authority. Cambyses's mother was Cassandane, another member of the Achaemenid family.
In just over a decade Cyrus had gone from being ruler of Persis, a small satellite state of the Median Empire, to ruling an empire of his own that included the former Median Empire, the kingdom of Lydia in Asia Minor (along with a string of Greek coastal cities) and the Babylonian Empire. Cyrus died in battle in the north-eastern corner of his empire, somewhere in the region of the Oxus and Jaxartes Rivers, in 529 BC.
Cambyses had carried out some royal duties before his father's death. In 538 he was recorded as carrying out the king of Babylon's role in the New Year festivals, and in 530 he was appointed regent for his father before he left to campaign in the east. He was vice-king in Babylon, with his residence at Sippar.
Cyrus left at least two sons. The Empire went to Cambyses, who in order to secure his rule executed his brother Bardiya (or Smerdis). He then turned his attention to Egypt, the last remaining independent major power in the region. At the start of his reign Egypt was ruled by Ahmose II, a long-lived Pharaoh of the 26th Dynasty. Ahmose hired Greek mercenaries in an attempt to defend his kingdom, but was apparently betrayed by Phanes, one of their generals, before the Persian invasion. Ahmose died before the Persian invasion, and was succeeded by his son Psamtik III.
Cambyses invaded in 525 (Greco-Persian War). He successfully crossed the Sinai Desert, showing that he could conduct difficult operations. He then defeated the Egyptians in battle at Pelusium before besieging the survivors at Memphis. The city was soon captured. Psamtik was taken prisoner and went into exile at Susa. Cambyses made some effort to be accepted by the Egyptians, and he was seen as the founder of a new Egyptian Dynasty, the 27th. He also gained the submission of the kings of Cyprus, who had previous acknowledged Ahmose II as their overlord.
Cambyses remained in Egypt for some time. According to Herodotus, who was generally hostile to him, he sent out three unsuccessful expeditions while in Egypt. One was directed against the Phoenician colony of Carthage, on the North African coast, but this had to be abandoned after his Phoenician sailors refused to take part. The second was sent against the Oasis of Amon in the desert west of the Nile. This army was said to have been destroyed by a sandstorm, a story that still attracts attention now. The third, led by Cambyses in person, was south into Nubia. This expedition was said to have been the most successful of the three, but the army suffered from a lack of supplies on the return journey.
After the failure of these three expeditions Cambyses settled down to secure his control of Egypt. He posted three garrisons - one at Daphnae in the eastern Nile Delta, one at Memphis near the start of the delta and one at Elephantine.
By now Cambyses had been away from the heart of his empire for a dangerously long period of time. In March 522 BC a revolt finally broke out against him, led by Gaumata the Magian, who claimed to be his brother Bardiya. The fake Bardiya offered to cancel taxes for three years, and gained support in some provinces of the Empire. Cambyses prepared to rush home to deal with the revolt, but died on the road. According to some accounts he committed suicide, but in others this was an accidental death, possibly caused by an infected sword injury.
With Cambyses gone the direct male of Cyrus ended. Another prince of the Achaemenid family, Darius, took command of Cambyses's army, and returned to Persia to crush the revolt. Darius I the Great became one of the most successful of the Persian Emperors, although he is best known now because of the failure of his invasion of Greece.
A different view of Cambyses comes from a text on a statue of Udjahorresnet, an Egyptian priest and doctor who served both the old regime and the new, and presented Cambyses in a positive light.