One theory for the Greek success in the battle is the lack of Persian cavalry. The theory is that the Persian cavalry left Marathon for an unspecified reason, and that the Greeks moved to take advantage of this by attacking. This theory is based on the absence of any mention of cavalry in Herodotus' account of the battle, and an entry in the Suda dictionary. The entry "χωρίς ἰππεῖς" ("without cavalry") is explained thus: The cavalry left. When Datis surrendered and was ready for retreat, the Ionians climbed the trees and gave the Athenians the signal that the cavalry had left. And when Miltiades realized that, he attacked and thus won. From there comes the above-mentioned quote, which is used when someone breaks ranks before battle.