What, then, was this “Foreign Legion”? M. Girard identifies it with the Mounted Archers, on the strength of a passage in Aristophanes’ _Birds_. An unknown deity has invaded the territory of Cloud-Cuckoo town. Peisthetairos exclaims, “Why didn’t you despatch peripoloi after him at once?” To which the messenger replies, “We did send 30,000 Mounted Archers.” The inscriptions at Eleusis also make a force of non-citizen troops serve under the captain of the peripoloi. These mercenary troops, having no civil duties, would naturally be used as a patrol. Moreover, to an Athenian, “archer” meant “policeman.” Athens was policed by foreign “Archers”: it would be natural for Attica to be policed in like manner, only by a mounted force, as a greater distance had to be covered.[636] But it is also possible that the non-Athenian peripoloi were the sons of μέτοικοι ἰσοτελεῖς [metoikoi isoteleis], who, being forced to serve as hoplites when grown up, would require some preliminary training; these alien hoplites are coupled by Thucydides[637] with the recruits and veterans, who garrisoned the Athenian walls and forts: they seem to have served as a perpetual patrol. The first three classes of Athenian citizens in wealth must all have passed through this training; for, although the two first were liable to cavalry service, they might also be called upon to serve as hoplites.[638] Rich young epheboi, who had plenty of time on their hands, would naturally learn both cavalry and infantry drill. The poorer Zeugitai would only have to learn their duties as heavy infantry, and were probably allowed to spend a good proportion of their time on their farms in Athens. But what about the fourth class, the Thetes? They were not liable to be called out as hoplites, but had to serve on land as light-armed troops or at sea as rowers. Did they also have a recruit course? Now the garrisons of the Athenian forts and walls were hoplites:[639] there is no trace of the Thetes here. But the patrol duties in the mountains can hardly have been performed by heavy troops: it is noticeable that in Xenophon light troops are suggested for this purpose, when Sokrates is developing an elaborate scheme for holding the frontiers of Attica against all invaders.[640] In the next century, at any rate, light troops were used for this purpose. In a later work Xenophon talks of “those who are ordered to occupy the forts and those who have to serve as peltasts and patrol the country,”[641] in a passage where he is clearly referring to the epheboi. Thus there are two classes, the garrisons, who would naturally be hoplites, and the patrols, who are peltasts, suitably equipped for mountaineering. But the peltasts only began to appear towards the close of the Peloponnesian War: the first mention of them is in Thucydides’ account of the army of Brasidas. Before this time, the light troops were archers and some slingers; thus, in the monument