E.C. Marchant, Commentary on Thucydides Book 1

9 ἐνιαυτὸς μὲν οὐ δ., ἔλασσον δέ—this certainly emphasises the length of time occupied, in spite of their haste, and not the promptitude of the coufederacy; the latter would be inconsistent with all that precedes (c. 71. 4; 124. 1, and this section). Thuc. means clearly (it seems to me), ‘I was going to say a year was consumed: but no, it was less than that’; i.e. it was not much less. (1) In 2.2, if the text is sound, we read that the entry into Plataea took place at the very beginning of spring 431, and in the sixth month after the battle of Potidaea (see c. 62); and (2) we are further told that the first invasion of Attica was eighty days after the seizure of Plataea. Hence the whole time between the battle of Potidaea and the first invasion would be less than nine months, and to arrive at the length of time that separates the resolution of the confederacy from the first invasion, we must deduct the time occupied by the events narrated in cc. 63-88 and 118-125, which are:

1. The Athenians built a wall on north side of Potidaea and garrisoned it

2. χρόνῳ ὕστερον Phormio was sent from Attica with 1600 hoplites, and κατὰ βραχὺ προήει.

3. Phormio built a wall south of Potidaea.

4. The Corinthians called a meeting at Sparta. (At what exact stage of affairs this was done is not clear.)

5. The Spartans sent to Delphi.

6. The general meeting was held at Sparta, and the decision taken.

Hence the time would be much less than a year; and it is probable that the μηνὶ ἕκτῳ of 2.2 is somehow coriupt.

πρὶν ἐσβαλεῖν—under Archidamus. The account of it is in 2.19.