E.C. Marchant, Commentary on Thucydides: Book 3

θέρους—Thuc. divides the year into θέρος, consisting of about eight months (Elaphebohon to Pyanepsion) and χειμών, consisting of about four (Maimacterion to Anthesterion).

ἅμα τῷ σίτῳ ἀκμάζοντι—‘just when the corn was ripening’; about the middle of May, 428 B.C., before the harvest (καρποῦ ξυγκομιδή).

ἐγκαθεζόμενοι—the form serves as an aorist as well as a present.

ὥσπερ εἰώθεσαν—sc. γίγνεσθαι, in the two previous invasions. The plan had been started by Pericles.

ὅπῃ παρείκοι—impers., though strictly ὁ θεός is the subject implied.

τὸν πλεῖστον ὅμιλον—cf. II. 31 ὁ ἄλλος ὅμιλος ψιλῶν, ‘the main body.’ Outside Thuc. ὅμιλος is found only in Herod., in tragedy, and in late authors.—The wasting of the country was a tedious task that would devolve naturally on the light-armed troops.

εἶργον τὸ μή—for the constr., which is common with verbs and phrases signifying prevention (Aesch. PV. 252 ἐξελυσάμην βροτοὺς | τὸ μὴ . . μολεῖν, and often in Aesch.) cf. VI. 1 διείργεται τὸ μὴ ἤπειρος εἶναι (where the MS. οὖσα is shown by many imitations of the sentence by later authors to be a mistake).

τῶν ὅπλων = τοῦ στρατοπέδου, strictly the space in front of the quarters where the arms were stacked; here the word marks the fact that the light-armed could not with safety be withdrawn from the hoplites. 10. τὰ ἐγγὺς τῆς πόλεως—i.e. houses, trees, vineyards: we are not to suppose that the Athenians cropped their lands annually for the benefit of the Peloponnesian invaders.

οὗ—the gen. as in μισθὸς τριῶν μηνῶν. The enemy remained in Attica about thirty days: the longest invasion, that of 430 B.C., lasted forty days, the shortest, in 425 B.C., fifteen days.