Laudator Temporis Acti

H.T. Wade-Gery, The Poet of the Iliad (Cambridge: Cambridge University Press, 1952), p. 2, with note on p. 62:

When Achilles shouts from the trench, Homer likens it to the sound of the trumpet:

XVIII 219 Like the loud music, when the trumpet calls
        220 Because the city is circled with the foe,
              Came the loud music of Achilles' call.

'The heroes do not know of the trumpet, the poet does' is the ancient comment on these lines: he is describing some sudden danger to a Greek city within his own experience; as when the Kolophonian exiles seized Smyrna, or troops from Chios captured Erythrai.⁵

5 (p. 2) Smyrna: Herodotos, I 150. Erythrai: Athenaeus, 259 (= Hippias of Erythrai, FGH, 421 F 1). These two attempts succeeded: in both the city was undefended in daytime because of a Panegyris: in the second we are expressly told that 'the trumpet was heard suddenly' (Athenaeus, 259 B). The Ephesians of the first generation captured Samos, and ten years later were turned out (Pausanias, VII 4 2-3): for the capture of Melia see note 10. More often, no doubt, such attempts would be beaten off.

Homer, Iliad 14.219-221:

ὡς δ᾽ ὅτ᾽ ἀριζήλη φωνή, ὅτε τ᾽ ἴαχε σάλπιγξ
ἄστυ περιπλομένων δηΐων ὕπο θυμοραϊστέων,
ὣς τότ᾽ ἀριζήλη φωνὴ γένετ᾽ Αἰακίδαο.

Scholion (Erbse, Vol. IV, p. 474):

αὐτὸς μὲν οἶδε σάλπιγγα, οὐκ εἰσάγει δὲ ἥρωας εἰδότας.