Thucydides 7.28.3 (tr. Charles Forster Smith):
But what most oppressed them was that they had two wars at once, and had thus reached a pitch of frenzy which no one would have believed possible if he had heard of it before it had come to pass.
μάλιστα δ᾽ αὐτοὺς ἐπίεζεν ὅτι δύο πολέμους ἅμα εἶχον, καὶ ἐς φιλονικίαν καθέστασαν τοιαύτην ἣν πρὶν γενέσθαι ἠπίστησεν ἄν τις ἀκούσας.
Frenzy doesn't seem quite right for φιλονικίαν
. Cf. Jeremy Mynott's translation with his note:
But what put most pressure on the Athenians was that they were conducting two wars at the
same time, and they brought to them a competitive spirit1 that had to
be seen to be believed.
1 Philonikia, literally 'love of victory': a further explanation of the Athenians' motivation in Sicily, this time an authorial one in terms of the Athenian character (see VI 47n).
A.W. Gomme et al. ad loc.: