The first oracle is about Egypt.
The first part of the oracle (Jeremiah 46:2–12) is concerning the army of Pharaoh Neco, king of Egypt, which was by the river Euphrates at Carchemish and which Nebuchadnezzar king of Babylon defeated in the fourth year of Jehoiakim the son of Josiah, king of Judah.
This refers to the battle of Carchemish which took place in 605 BC. It was at this battle that Babylon won a crushing and decisive victory against Egyptian and Assyrian forces. This marked the end of Assyrian dominance and the beginning of Nebuchadnezzar’s rise to power. Egypt had begun their onslaught against Babylon in 609 BC when Pharoah Neco marched north to assist Assyria against Babylon. Josiah attempted to intervene by attacking the Egyptians at Migdol, but he was tragically killed in battle. The Egyptians went on to confront Babylon and experienced their first defeat at Haran. Even though they were defeated, the Egyptians still exercised considerable power over Judah and so they invaded Jerusalem, took Jeconiah into exile and placed Jehoiakim, who was pro-Egypt, on the throne (2 Kings 23:31–35; 2 Chronicles 36:1–8). After the battle of Carchemish, Babylon took control of Judah and the surrounding nations. The words of the oracle in Jeremiah 46:3–12 were composed either just before or just after Nebuchadnezzar defeated the Egyptians.1 .
2 About Egypt. Concerning the army of Pharaoh Neco, king of Egypt, which was by the river Euphrates at Carchemish and which Nebuchadnezzar king of Babylon defeated in the fourth year of Jehoiakim the son of Josiah, king of Judah: