Croesus had not waited for the oracle to provide himself with sufficient support in his undertaking. Yet it suited him to enter into negotiations with the Spartans, who after a series of successful contests against the Pisatae, Argos, and some cantons of Arcadia, had obtained the foremost place in the Peloponnesus. At an earlier time Croesus had sent the Spartans a considerable present for the erection of a statue of Apollo, and their grateful feeling towards him would certainly be strengthened by the authority of the Delphian oracle, whose response was known to the Spartans, as Herodotus expressly states (p. 9). Even in Xenophon's account they declared themselves ready to send auxiliary troops to Sardis.[21] Croesus did not stop here: he sent Eurybatus to obtain yet more troops in Hellas. Herodotus told us that Croesus was in league with Egypt and Babylonia against Persia before he made the treaty with Sparta. Amasis, king of Egypt, had determined to support Croesus, perhaps in return for the service which Gyges had once rendered to Psammetichus, when he sent soldiers to aid him against his fellow-princes, the vassals of Assyria (III. 301). The attitude of Babylonia must be decisive. If Lydia and Babylonia, who were both equally threatened by the new power, united in a firm military alliance, they might hope to contend successfully with the prince of the Persians. At Babylon, after the accession of Nabonetus in the year 555 B.C., the royal power was again in strong hands. According to Herodotus, there was a league between Croesus and Nabonetus against Persia. Xenophon represents Croesus as coming to the aid of the king of Babylon. Justin states that Cyrus was at war with Babylon when Croesus attacked him; Cyrus drove him back, came to terms with Babylonia, and carried the war to Lydia. From all this we may assume that Lydia and Babylonia were united, and that they undertook the war against Persia in common.
Croesus then might consider that careful preparations had been made for his enterprise, when in the year 549 B.C., and as we may pre-suppose with certainty, in the spring of the year, he took the field.[22] He crossed the Halys, and directed his course to the commanding plateau of Pteria, which Herodotus rightly regards as the strongest position in those regions. He took Pteria, and the neighbouring cities, and laid waste the land, with the view no doubt of making it impossible for the Persian army to support itself. There he remained, either because he shrank from going further, and seeking a decisive conflict at a distance from his own borders, or because he expected a diversion on the part of the Babylonians.