en_tn/jer/04/21.md

How long will I see the signal flag? Will I hear the sound of the horn?

Jeremiah uses these questions to show his distress about seeing the battle flag and hearing the sound of the horn for such a long time. He wishes that the battle would end soon. It can be stated as an exclamation. Alternate translation: "Oh, how I wish that the battle would end, and the flag would be lowered, and the sound of the army's horn would stop" (See: rc://en/ta/man/jit/figs-rquestion)

the sound of the horn

Someone would blow the horn as a signal for battle.