Jeremiah received the LORD's word when Babylon's King Nebuchadnezzar and his army, and all the countries and people he ruled, were attacking Jerusalem and all its towns.
References for Jeremiah 34:1
The LORD, the God of Israel, proclaims, Go and speak to Judah's King Zedekiah and say to him: The LORD proclaims, I'm handing this city over to the king of Babylon, and he will burn it down.
You won't escape but will be captured and handed over to him. You will see the king of Babylon with your very own eyes and speak to him personally, and you will be taken to Babylon.
Even so, hear the LORD's word, King Zedekiah of Judah: This is what the LORD proclaims about you: You won't die in battle;
you will die a peaceful death. As burial incense was burned to honor your ancestors, the kings who came before you, so it will be burned to honor you as people mourn, "Oh, master!" I myself promise this, declares the LORD.
The prophet Jeremiah delivered this message to Judah's King Zedekiah in Jerusalem
when the army of the king of Babylon was attacking Jerusalem and all the remaining Judean towns, Lachish and Azekah—the only fortified towns still standing in Judah.