οὐ γάρ πω ἰδόμην, οὐδ’ ἔκλυον αὐδήσαντος / ἄνδρ’ ἕνα τοσσάδε μέρμερ’ ἐπ’ ἤματι μητίσασθαι
See also below at 10.289–290 and 10.524 for more on μέρμερα ἔργα. Agamemnon gives important details as to just what is “astounding” about what Hektor did on the battlefield. He has never seen or even heard tell of one man devising so many astounding deeds in one day. Hektor’s deeds on the battlefield are unprecedented in Agamemnon’s experience, and are of course the reason why he is sleepless this night. The language even juxtaposes the “one” and “so many”: mermera erga are accomplished by one man (or two men, as we shall see) who kill many more. In the next day’s battle, too, Hektor is reported to be accomplishing mermera erga and destroying phalanxes of young men (Iliad 11.502–503). On mourning the loss of so many men in one day of battle cf. Aeschylus Persians 431–432.