We are not really given a reason for this expedition, though it would seem that such voyages were made for economic gain. Considering the control of the northern shores of the Mediterranean by the Greeks and of the southern coasts by the Phoenicians, the only region where Egypt, with its inferior fleet, might acquire some influence and wealth would have been eastern Africa, where they had already established some trade. However, it has also been suggested that the voyage might have served a military purpose.

According to Herodotus, Necho II ordered a Phoenician-crewed fleet to leave Egypt from the east by way of the Gulf of Suez and to return via the Straits of Gibraltar at the Mediterranean's western mouth. Hence, he expected this expedition to navigate around Africa counterclockwise. This would be a long journey, in which the crew would help support themselves by establishing temporary settlements on land where they would cultivate crops during the voyage.

According to the story, after two full years the fleet eventually rounded the Pillars of Hercules (the Straits of Gilbraltar), and returned to Egypt during the course of the third year. 

Herodotus finishes the story with a surprising conclusion:

"the Phoenicians made a statement which I myself do not believe (though others may if they wish) to the effect that they sailed west around the southern end of Africa, they had the sun on their right". 

This is exactly what they would have seen going west around the Cape of Good Hope at the southern tip of Africa, because the sun appears to the right when traveling westward in the southern hemisphere, but how could Herodotus have known this at such an early date if the journey did not take place. 

Outside of Herodotus' account, there is little or no evidence of such a voyage. However, most of his story appears to at least be plausible, and it should be noted that this voyage took place not so very distant from Herodotus' own time. His Histories were written in about 440 BC, while Necho II came to the Egyptian throne in about 610 BC. 

The Egyptians would have known, for some time, a certain length of Africa's east coast, for they had from earlier times been making visits to the land of Punt. Though Punt's exact location remains unknown, it was almost certainly on Africa's east coast somewhat south of Egypt. The Phoenicians had been in contact with the Atlantic since the trading port of Gadir (modern Cadiz) was founded in about 800 BC. They also possessed ships that were capable of sailing through the Straits of Gibraltar and along the North African coast, so technically a trip around Africa would have been possible. In fact, the winds and currents favor an east-west circumnavigation of Africa, and navigation would have been no problem if they kept the coast in sight. Furthermore, the Egyptians had for many years undertook sea voyages to Byblos, on the Levantine coast, and to Punt by way of the Red Sea. Though the circumnavigation of Africa under Vasco da Gama, who sailed from Lisbon in Portugal to Calicut in India, took only ten months between 1497 and 1498, the two and a half year journey of the Phoenician ships also seems reasonable, especially considering their layover to replenish their supplies. 

The tale is also consistent with the foreign policy of Necho II, who sought to benefit Egypt economically by improving access to sea routes. He is credited with probably starting the construction (or restoration) of a canal some 85 kilometers long and wide enough for sea going ships, connecting the Nile Valley with the Red Sea. This canal, foreshadowing the modern Suez canal, later became an internationally important trade route.

However, while many readers of Herodotus have taken this story for granted, it does not in fact prove that Necho II's fleet did circumnavigate Africa. It must be remembered that Herodotus' Histories is an elaborate piece of rhetorical writing, and is not an objective history, but rather a highly literary, as well as partisan, analysis of the cultural clash between the Greek and Persian cultures. He was a Greek who was convinced of Greek superiority, and his favorite technique of devaluing Persian achievements was to emphasize what other non-Greeks (especially Egyptians) could achieve. 

He also loved recounting stories of Egyptian kings solving difficult problems, showing the depth of Egyptian wisdom, which of course the Persians could not match.

Hence, because we have no direct evidence of this journey around Africa from contemporary Egyptian sources, it is likely that it never took place. In fact, Egyptologist Alan Lloyd believes the adventure extremely unlikely, stating that: 

"If an Egyptian king, at any period, organized and dispatched an expedition, he did so for specific practical ends to meet specific practical needs. Disinterested inquiry or plain curiosity were always amongst the least evident of Egyptian habits of mind. What possible end could an Egyptian king have thought an enterprise of this sort might have served? To anyone familiar with Pharaonic ways of doing things the reply immediately prompted is an emphatic 'None at all!'. Given the context of Egyptian thought, economic life, and military interests, it is impossible for one to imagine what stimulus could have motivated Necho in such a scheme and if we cannot provide a reason which is sound within Egyptian terms of reference, then we have good reason to doubt the historicity of the entire episode."

Nevertheless, this story is a favorite of those who would connect the culture, and specifically the pyramids of Mexico with that of the Egyptians. They argue that ships could have been separated from Necho's fleet, blown westward across the Atlantic's narrowest part, ending up on the Brazilian cost. From there, it would have been possible for them to sail north to the Mexican Gulf, where they might have landed and established a colony, spreading Egyptian culture throughout Central and South America. However, this possibility is itself once removed from a tale that must be questioned. 

References: