Sometime in the mid-second century A.D., Lucius Flavius Arrianus—a Greek-speaking prominent Roman citizen from Nicomedia, in northwest Asia Minor near the Bosporus—wrote a history of Alexander the Great’s eleven-year-long “march up country” that began with the invasion of Persian Ionia and ended some 3,000 miles distant at the Indus River. The well-connected and well-read Arrian tried to emulate formal classical Greek prose of a distant age, and he probably modeled his history of Alexander after Xenophon’s more famous Anabasis, which chronicled a far earlier Western march of the mercenary Greek “Ten Thousand,” who in 401 B.C. fought their way home from Babylon after the death of their boss, the Persian would-be royal usurper Cyrus the Younger.

Nearly five hundred years after the death of Alexander, in the age of the emperor Trajan, the creator of the Hellenistic world still held the popular imagination. Arrian wrote a largely favorable account of Alexander in hopes of enlightening his Roman audience about the truth of the legendary conqueror “for the benefit of mankind.” That he fought under Trajan and held responsibilities for eastern frontier defense no doubt made Arrian sensitive to the sort of cultural, military, and political challenges that Alexander had once faced in Asia. Arrian was a military thinker as well: he wrote a Tactica, an extant abstract work on the nature and organization of the Macedonian phalanx and cavalry that drew heavily on mostly lost Hellenistic tacticians—and which was not always relevant to the conditions of