וַיֹּ֤אמֶר אֲלֵהֶם֙ רִדְפ֣וּ אַחֲרַ֔י כִּֽי־נָתַ֨ן יְהוָ֧ה אֶת־אֹיְבֵיכֶ֛ם אֶת־מוֹאָ֖ב בְּיֶדְכֶ֑ם וַיֵּרְד֣וּ אַחֲרָ֗יו וַֽיִּלְכְּד֞וּ אֶת־מַעְבְּר֤וֹת הַיַּרְדֵּן֙ לְמוֹאָ֔ב וְלֹֽא־נָתְנ֥וּ אִ֖ישׁ לַעֲבֹֽר׃
Et il leur dit: "Suivez-moi! car l’Éternel livre en vos mains vos ennemis, les Moabites." Et ils descendirent à sa suite, occupèrent les gués du Jourdain conduisant en Moab, et ne laissèrent passer personne.
Rashi
Charge behind me to wipe out all the Moabites on our side of the Yardein.
Metzudat David
They chased after: its to say that they went quickly
Rashi
Took control of the Yardein passes so that the Moabites could not cross to escape and return to their country.