This compressed lion simile describing Diomedes’ slaughter of the Thracians calls our attention to the lion similes elsewhere in the Iliad that happen explicitly at night. The shepherdless flocks in this simile correspond well to the Thracians who sleep unguarded, and the absence of a shepherd suggests that, like Diomedes, the lion is attacking at night. To support this argument, we can compare the slightly longer simile at Iliad 15.323–326, where the attackers also find the herds or flocks unguarded:
οἳ δ’ ὥς τ’ ἠὲ βοῶν ἀγέλην ἢ πῶϋ μέγ’ οἰῶν
θῆρε δύω κλονέωσι μελαίνης νυκτὸς ἀμολγῷ
ἐλθόντ’ ἐξαπίνης σημάντορος οὐ παρεόντος,
ὣς ἐφόβηθεν Ἀχαιοὶ ἀνάλκιδες·
They, like a herd of cattle or large flock of sheep
that two wild beasts in the dead of dark night drive to confusion
when they come suddenly and no herdsman is present,
just so the Achaeans, with no battle resolve, were routed.
In this simile, two wild beasts, which Lonsdale (1990:66, 131) identifies as lions, attack. Important details here include the time, the dead of night, and the lack of a shepherd, just as in 10.485. The sudden appearance of the lions (ἐλθόντ’ ἐξαπίνης) is likewise similar to ambush language, in which the attacker appears out of the darkness or his hiding place to surprise his victims (compare 10.496–497 below for how the poetic language represents such a sudden appearance of an ambusher). Because this simile has so much in common with the one at 10.485–488, we can draw the inference that the simile of Diomedes’ attack is also imagined to be happening in the dead of night, but that compression has left that detail implicit. We can compare also Iliad 12.299–308, where Sarpedon is compared to a lion trying to get inside the πυκινὸν δόμον (Iliad 12.301) of the sheep—that attack is also likely to be taking place at night, when the sheep are in their pen. See 10.5–9 for more on the relation of the adjective pukinos to the ambush theme. The lion attacks because he is hungry, but also because his audacious spirit bids him to: κέλεται δέ ἑ θυμὸς ἀγήνωρ, Iliad 12.300. Compare the “audacious spirit” that motivates both Diomedes (10.220) and Dolon (10.319) to undertake the spying missions.
We see lions attacking flocks explicitly at night in still other similes, such as at Iliad 11.172–178, where the Trojans are compared to cattle when a lion has panicked the whole herd. In that simile, similar to Iliad 15.324, the time, the dead of night, is indicated by the phrase ἐν νυκτὸς ἀμολγῷ (Iliad 11.173; see also Tsagalis 2008:153–187 for more on this phrase and what he sees as its Indo-European imagery, connected to cattle, the sun, and danger), and the fear and confusion of the herd animals is a central feature (ἐφόβησε, Iliad 11.173), while death comes to one in particular (Iliad 11.174–176). This fear and confusion is replayed on the battlefield as Agamemnon routs the Trojans, but the simile itself has the feeling of an ambush. Lonsdale (1990:118–122) has also argued that lion and cattle similes like this one adapt the epic theme of the cattle raid. See “The Poetics of Ambush” for the cattle raid as part of the ambush theme.
In two of the similes of lions attacking at night, similes that share much of the same formulaic language, the lion is unsuccessful because of the watchfulness of the men and dogs who guard them (Iliad 11.546–557 and Iliad 17.655–666). In these examples, we see that they must keep watch all night long (πάννυχοι ἐγρήσσοντες, Iliad 11.551 and Iliad 17.660), and it is only at dawn that the lion finally withdraws (Iliad 11.555 and Iliad 17.664). These lions, who go away empty-handed, provide a contrast to what we see depicted at 10.485–488, where the lack of a shepherd watching the herd enables the lion to successfully attack: in the simile world, a steadfast night watch can counteract ambush tactics. We can also hearken back to the watchdog simile at 10.180–189 and see that comparison as an indication both that the wakeful and watchful Achaean guard is indeed the kind needed on this dangerous night and that it is a mistake on the part of the Thracians to fall asleep without a guard to watch over them. Lion similes, so common in the narration of fighting in the polemos, also have affinities with the ambush theme, and a lion attacking at night should especially be seen in this light. That lion similes work for both themes can also be taken as another indication that the two types of warfare are not diametrically opposed, just as we have seen warriors such as Diomedes himself, but also Achilles, who excel at both. See also Schnapp-Gourbeillon 1981:104–131 for her extended discussion of Diomedes the lion in Iliad 10.