Albert Barnes Commentary Jeremiah 46:12

"The nations have heard of thy shame, and the earth is full of thy cry; for the mighty man hath stumbled against the mighty, they are fallen both of them together." — Jeremiah 46:12 (ASV)

The land – The earth; the world rings with the cry of grief.

Against the mighty – Against the mighty man, i.e., one mighty man against another. The champions hired to fight Egypt’s battle get in one another’s way, and so are slaughtered together.