Isaiah 13 begins a denunciation against Babylon. The Lord would use a huge army to destroy Babylon (See verse 4). That day would be awful and so Isaiah wrote,
Wail, for the day of the LORD is at hand! It will come as destruction from the Almighty. (Isaiah 13:6)
The day of the Lord for His enemies would not be a day of rescue, but of horrible destruction. As proof, consider where Babylon is today!
Any nation that continues in sin shall experience a day of the Lord and the utter destruction that comes with it.