The Anabasis of Alexander/Book III/Chapter XX
CHAPTER XX.
March through the Caspian Gates.
Then taking the Companion cavalry, the light cavalry used for skirmishing, the Greek mercenary cavalry, under the command of Erigyius, the Macedonian phalanx, except the men who had been placed in charge of the money, the archers, and the Agrianians, he marched against Darius. In the forced march which he made, many of his soldiers were left behind, worn out with fatigue, and many of the horses died. He nevertheless pressed on, and on the eleventh day arrived at Rhagae.[1] This place is distant from the Caspian Gates one day's journey to one marching as Alexander did. But Darius had already passed through this defile before Alexander came up, though many of those who were his companions in flight deserted him on the way and retired to their own abodes. Many also surrendered to Alexander. The latter now gave up the hope of capturing Darius by close pursuit, and remained there five days to give his troops repose. He appointed Oxodates a Persian, who had the ill fortune to be arrested by Darius and shut up at Susa, to the office of viceroy of Media; for this treatment was an inducement to Alexander to rely on his fidelity. He then marched towards Parthia; and on the first day encamped near the Caspian Gates, which he passed through on the second day as far as the country was inhabited.[2] Hearing that the country further on was desert, he resolved to procure a stock of provisions from the place where he was encamped, and accordingly sent Coenus out on a foraging expedition with the cavalry and a small body of infantry.