Albert Barnes Commentary Jeremiah 51:30

"The mighty men of Babylon have forborne to fight, they remain in their strongholds; their might hath failed; they are become as women: her dwelling-places are set on fire; her bars are broken." — Jeremiah 51:30 (ASV)

Have refrained from fighting - Or, have ceased to fight: in despair when they saw that the conflict was hopeless.

Holds - The word properly means an acropolis, and so any inaccessible place of refuge.

They have burned - That is, the enemy has burned.

Bars - That is, fortifications .