The horses of Rhesos are thematically significant in multiple ways. In one version of the story of Rhesos (see the Rhesos section of our essay “Tradition and Reception”), the so-called “oracle version,” Rhesos’ horses are intimately tied to the destiny of Rhesos and to that of Troy, since the oracle declares that, if Rhesos and his horses eat and drink at Troy, Rhesos will be invincible. The whiteness of the horses, as we see later in this episode (see commentary on 10.547), makes them highly visible even in the dark of night. (Schnapp-Goubeillon sees a ritual significance to their color, saying that a white horse is the sacrificial victim par excellence in horse cults, 1981:117.) Their size and swiftness, noted by Dolon here, also make them a valuable prize. The practical and symbolic importance of horses in general in the Iliad is evident in the singer’s questions that follow the catalog of ships: the narrator asks who had the “best” horses as well as who was the best warrior (Iliad 2.761–770). That is, horses seem to be as much a part of the competition to be the best as is excellence in battle. (The answer given to these questions is that Achilles and his horses were the best, but only after it has been said that Eumelos’ mares and Telamonian Ajax were the best so long as Achilles was absent.) The value of horses is also seen in Diomedes’ acquisition of his enemies’ horses in Iliad 5. When he gives instructions to Sthenelos to capture the horses of Aeneas at Iliad 5.263–273, the most prominent example, Diomedes says capturing them will win them good kleos (εἰ τούτω κε λάβοιμεν, ἀροίμεθά κε κλέος ἐσθλόν, Iliad 5.273), making their symbolic value glory itself.
The possibility of taking these horses, when added to the attractiveness of the target of the sleeping, unguarded Thracians, combines ambush with horse-rustling, a closely associated theme. We will consider below (at 10.513–514) whether the theme of horse-rustling affects the composition of this nighttime horse-stealing episode, as compared to the taking of horses in daytime battle. But just as we have seen that spying missions frequently become ambushes, so also can ambushes incorporate this type of night raid (see pp. 80–84 of “The Poetics of Ambush” for other examples).
Shewan 1911:179–180 has already dismissed the argument that the lack of reference to these horses subsequently in the Iliad is evidence that Iliad 10 is a late addition to the epic.