at that day: i.e. the day of 2 Kings 18:11.
bow. Put by Figure of speech Metonymy (of the Adjunct), App-6, for the armies of Israel.
Related Commentaries of Hosea 1:5
Hosea 1:5
5 And it shall come to pass at that day, that I will break the bow of Israel in the valley of Jezreel.