Her hired soldiers in her midst is somewhat redundant. It would be sufficient to say “her hired soldiers” (Good News Translation). The reference is to the soldiers mentioned in verse 9.

Fatted calves; that is, calves kept in a stall and fattened to supply meat on special occasions. Good News Translation sees here the sense of helplessness: “helpless as calves.” Die Bibel im heutigen Deutsch renders “have become fat as calves,” and Bible en français courant is similar to this with “have been well taken care of.” This interpretation also makes sense in the context: “Even the hired soldiers who have been so well taken care of, the way people fatten up their calves, have all turned and fled.”

They have turned and fled … they did not stand: Good News Translation has restructured this to follow the order in which the actions happened, rendering “They did not stand and fight; all of them turned and ran.”

The day of their calamity is the same as the time of their punishment, and so it is possible to combine the two expressions: “when the LORD settles accounts and brings destruction on them.” Note that the one who brings the calamity and punishment is the LORD: “For the day has come when the LORD will bring disaster and punishment to them.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on Jeremiah. (UBS Helps for Translators). New York: UBS, 2003. For this and other handbooks for translators see here .