The Histories · 9.17

Mardonios then being encamped in Boeotia, the rest of the Hellenes who lived in these parts and took the side of the Medes were all supplying troops and had joined in the invasion of Attica, but the Phokians alone had not joined in the invasion,—the Phokians, I say, for these too were now actively taking the side of the Medes, not of their own will however, but by compulsion. Not many days however after the arrival of Mardonios at Thebes, there came of them a thousand hoplites, and their leader was Harmokydes, the man who was of most repute among their citizens. When these too came to Thebes, Mardonios sent horsemen and bade the Phokians take up their position by themselves in the plain. After they had so done, forthwith the whole cavalry appeared; and upon this there went a rumour through the army of Hellenes which was with the Medes that the cavalry was about to shoot them down with…

Herodotus of Halicarnassus · trans. G. C. Macaulay, 1890
Source edition
Passage preview. Read in context for the complete text, notes and references.