ἐπὶ κέρας, ‘in column.’ Att. ἐπὶ κέρως (Thuc. ii. 90, &c.). For the accus. cf. vi. 111. 3; ix. 31. 2 ἐπὶ τάξις.
ὅκως: not final ‘in order that’ (Krüger), but temporal ‘as often as’ (Stein, Macan). In sense co-ordinate with ἔχεσκε παρεῖχε τε. Cf. i. 17. 2.
διέκπλοον. This manœuvre (cf. ch. 15. 2) is again mentioned at Artemisium (viii. 9), but was first used with effect by the Athenians in the Peloponnesian War (Thuc. ii. 83, 89, &c.), its absence in the battle of Sybota proving the inferior skill of the Corinthian and Corcyrean navies (Thuc. i. 49). It consisted in breaking through the enemy's line, and then turning rapidly to ram one of his ships on its defenceless side or stern. It demanded great skill in the coxswain and efficiency in the oarsmen. It was met by forming in a circle with prows outward (cf. viii. 11), a device which proved useless against Athenian daring and skill (Thuc. ii. 83), or by drawing up the ships on the wings in a double line (Xen. Hell. i. 6. 29-31), or by having a second line in reserve (v. 121 n.). If H. is not guilty of an anachronism, the Athenians only perfected a manœuvre practised by the Ionians. Sosylus even makes it a Phoenician device brilliantly met by Heraclides (v. 121 n.).
The grievance was that Dionysius kept the sailors on board practising manœuvres, and the marines under arms all day, in stead of letting them enjoy themselves ashore like an army in tents.
ἐκπλώσαντες. For the metaphor, here strikingly appropriate, cf. iii. 155. 3.