The fierce anger of the Lord - i. e., against Babylon. The people of God are to flee away that they may not be involved in the miseries of Babylon. See the Jeremiah 50:8 note.
Related Commentaries of Jeremiah 51:45
Jeremiah 51:45
45 My people, go ye out of the midst of her, and deliver ye every man his soul from the fierce anger of the LORD.