Carchemish is a region in northern Israel, on the upper reaches of the Euphrates River. Although it was under the rule of Assyria, during a period when Assyria's power was weakening and the power of King Nebuchadnezzar of Babylon was growing strong, Pharaoh Necho of Egypt advanced to this place to stop Nebuchadnezzar, and was greatly defeated in battle with Babylon.
At this time, King Josiah blocked the Egyptian army attacking Carchemish. Because he hated Assyria, he blocked Necho's army, which would have helped Assyria, from passing through his territory.
However, in this battle, the army of the Kingdom of Judah was defeated, and Josiah also died. Necho also captured Jehoahaz, who ascended to the throne after Josiah's death.
Later, in the fourth year of King Jehoiakim's reign,
Necho fought Nebuchadnezzar at Carchemish, and was greatly defeated there, making Babylon virtually the victor in the Near East.