T. G. Tucker, Commentary on Thucydides: Book 8

οἱ μετὰ Χαλκιδέως the same as τοὺς ἀπὸ τῶν ἑαυτοῦ νεῶν ὁπλίτας of c. 23, § 4; his ἐπιβάται and other men. The Peloponnesian crews have been left at Chios (c. 17, § 1) and have remained there (c. 32, § 2).

ξενικὸν ἐπικουρικὸν Herwerden, followed by P-S and others, brackets ξενικὸν, and similarly in iii. 109, τὸν μισθοφόρον ὄχλον τὸν ξενικόν, where Meineke, however, would bracket μισθοφόρον. It is urged that the expression is tautological, or at least pleonastic. So, therefore, in a milder form, would be iv. 52, μισθωσάμενοι ἐπικουρικόν (and ii. 33). InXen. Hell. vi. 1, 5, μισθοφόρους ἔχω ξένους, Dindorf and Cobet would eject μισθοφόρους. In Thucyd. vi. 55 ἐπικούροις is opposed to πολίταις. Now ἐπίκουροι literally conveys only the notion of auxiliary forces, and only by suggestion that of mercenaries. In vii. 58, ἐπικουρίαι has not the latter implication at all. Τισσαφέρνους ἐπικουρικὸν might mean nothing more than an auxiliary force sent by T. The addition of ξενικὸν defines the force as consisting of ξένοι (i. 121, vii. 42). If any word is to be expunged it would rather be ἐπικουρικόν, for it might be claimed that all ξένοι are ἐπίκουροι. But the pleonasm is scarcely felt: ‘a certain auxiliary force of mercenaries belonging to Tissaphernes.’