John Gill 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 nations have heard of your shame
Their shameful defeat and overthrow by the Chaldean army; so, after the manner of prophecy, the thing is related as done; the battle fought, and the victory obtained; and the rumour and fame of it spread among the nations, to the great mortification of this proud people:

and your cry has filled the land ;
the shrieks of the wounded; the cry of the pursued and taken; the lamentation of friends and relations for their dead; with one thing or another of this kind the whole land of Egypt was filled; yes, all the countries round about them, in confederacy with them, were filled with distress for the loss of their own; the calamity was large and spreading, and the rumour of it:

for the mighty man has stumbled against the mighty, and they are
fallen both together ;
either the mighty Egyptians against the mighty Chaldeans; and though the latter were the conquerors, yet lost abundance of men; so that there were mighty ones fell on both sides: or rather, as Jarchi, Kimchi, and Abarbinel, the mighty Egyptians in their flight fell, and other mighty ones of them following, stumbled at them, and fell upon them, and so both became a prey to the pursuers; or in their flight the mighty Egyptians stumbled against their mighty auxiliaries before mentioned, (Jeremiah 46:9) ; and so both came into the hands of their enemies. The Targum is, both were slain.