2 Chronicles 35:20

After all this when Josiah had prepared the temple Necho king of Egypt came up to fight against After all this, when Josiah had prepared the temple, Necho king of Egypt came up to fight against Carchemish by Euphrates: and Josiah went out against him.

After all this, when Josiah had prepared the temple. He most probably calculated that the restoration of the divine worship, with the revival of vital religion in the land, would lead, according to God's promise, and the uniform experience of the Hebrew people, to a period of settled peace and increased prosperity. His hopes were disappointed. The bright interval of tranquillity that followed his re-establishment of the true religion was brief. But it must be observed that this interruption did not proceed from any unfaithfulness in the divine promise, but from the state into which the kingdom of Judah had brought itself by the national apostasy, which was drawing down upon it the long-threatened, but long-deferred judgments of God.

Necho king of Egypt came up to fight against Carchemish by Euphrates. Necho, son of Psammeticus, succeeded to the throne of Egypt in the 20th year of Josiah. He was a bold and enterprising king, who entered with all his heart into the struggle which the two great powers of Egypt and Assyria had long carried on for the political ascendancy. Each, jealous of the aggressive movements of its rival, was desirous to maintain Palestine as a frontier barrier.

After the overthrow of Israel the kingdom of Judah became in that respect doubly important; and although the king and people had a strong bias for alliance with Egypt, yet from the time of Manasseh it had become a vassal of Assyria; and although in the civil wars that were waged between Assyria and Babylon, Nineveh had fallen, and the Babylonian power was on the ascendant, Josiah, true to his political no less than his religions engagements, thought himself bound to support the interests of his northern liege-lord. Hence, when "Necho king of Egypt came up to fight against Carchemish ... Josiah went out against him."

Carchemish, on the eastern side of the Euphrates, was the key of Assyria on the west; and in going there the king of Egypt would transport his troops by sea along the coast of Palestine, northwards. Josiah, as a faithful vassal, resolved to oppose Necho's march across the northern parts of that country. They met in the "valley of Megiddo" - i:e., the valley or plain of Esdraelon. The Egyptian king had come either by water or through the plains of Philistia, keeping constantly along the coast round the northwest corner of Carmel, and so to the great plain of Megiddo. This was not only his direct way to the Euphrates, but the only route fit for his chariots, while thereby also he left Judah and Jerusalem quite to his right. In this valley, however, the Egyptian army had necessarily to strike across the country; and it was on that occasion that Josiah could most conveniently intercept his passage. To avoid the difficulty of passing the River Kishon, Necho kept to the south of it, and must therefore have come past Megiddo. Josiah, in following with his chariots and horsemen from Jerusalem, had to march northwards along the highway through Samaria by Kefr-kud (the ancient Caper-cotia) to Megiddo (Van de Velde).