John Calvin Commentary Jeremiah 50:37

"A sword is upon their horses, and upon their chariots, and upon all the mingled people that are in the midst of her; and they shall become as women: a sword is upon her treasures, and they shall be robbed." — Jeremiah 50:37 (ASV)

The Prophet, indeed, changes the gender of the pronouns and seems to refer to the king; but there is no ambiguity in the meaning; he then declares that the horses, as well as the chariots, would perish; for the sword would consume all the things used in war. And at the beginning he generally declared that destruction was near all the Chaldeans, so he repeats the same now, on all the promiscuous multitude, which is in the midst of Babylon. He says that they would be without courage, for the Lord would dishearten them by terror, as it will be stated again later. Then he adds, and on her treasures, and they shall be a prey to enemies.