As Aeneas inspects the pictures in Juno’s temple, he sees Hector dragged three times around the walls of Troy by Achilles:
Ter circum Iliacos raptaverat Hectora muros
exanimumque auro corpus vendebat Achilles. (483-4)
Vergil describes Aeneas’ reaction thus:
Tum vero ingentem gemitum dat pectore ab imo,
ut spolia, ut currus, utque ipsum corpus amici
tendentemque manus Priamum conspexit inermis. (485-7)
The triple repetition of ut corresponds to the triple-sensed ter in 483. Aeneas sees Hector dragged three times around the walls and gives forth a groan as he sees the (1) spoils, (2), chariots, and (3) the body of his friend and Priam’s outstretched hands (these last two being joined after the third ut). Note the expansion in the third member (tricolon crescens). The verb is delayed to the last-but-one word, and that choice is important: delaying inermis, of Priam’s hands, increases pathos.
Aeneas’ groan is reminiscent of an earlier one, discussed here.