According to Diodorus, the only detailed source for this campaign, the Persian relief force had pitched camp near the Nile. Although Herodotus does not cover this period in his history, he mentions as an aside that he "saw too the skulls of those Persians at Papremis who were killed with Darius' son Achaemenes by Inaros the Libyan". This provides some confirmation that this battle was factual, and provides a name for it, which Diodorus does not. Papremis (or Pampremis) seems to have been a city on the Nile delta, and a cult centre for the Egyptian equivalent of Ares/Mars. Diodorus tells us that once the Athenians had arrived, they and the Egyptians accepted battle from the Persians. At first the Persians' superior numbers gave them the advantage, but eventually the Athenians broke through the Persian line, whereupon the Persian army routed and fled. Some portion of the Persian army found refuge in the citadel of Memphis (called the 'White Castle'), however, and could not be dislodged. Thucydides's rather compressed version of these events is: "and making themselves masters of the river and two-thirds of Memphis, addressed themselves to the attack of the remaining third, which is called White Castle".