καὶ οἱ μὲν αὐτῶν εὐθὺς ἐν τῷ ποταμῷ ἔπεσον ἐν τῷ ποταμῷ ἔπεσον, οἱ δὲ ἄλλοι ἔφευγον
En dadelijk vielen sommigen onder hen in de rivier, maar de anderen ontkwamen.
The prepositions ἐν, ἐπί and πρός with the dative signal a direction.
As in the case of the dative without preposition, these constructions accompany verbs of motion such as βάλλω ‘to throw’, ἕζομαι ‘to sit down’, κλίνω ‘to lean’, ὀρέγω ‘to reach out’, πελάζω ‘to approach’, πήγνυμι ‘to fix in’, πίπτω ‘to fall’, ῥίπτω ‘to throw’ or τίθημι ‘to place’. These prepositions also occur with verbs which cannot take a simple dative (e.g. ἵζω or ἕζομαι ‘to sit’, ἵστημι ‘to draw up’ or θρῴσκω ‘to jump’).
By using ἐπί the speaker emphasises physical contact with the destination towards which one moves. The construction with ἐπί occurs with a far greater number of verbs than that with ἐν. When the goal of the direction is inanimate, the preferred construction is ἐπί with the accusative; otherwise the dative is preferred.