Second Chronicles 35:20-26 adds a footnote  to the terse account of Josiah’s defeat in II Kings 23:

After all this, when Josiah had set the temple in order, Neco of Egypt went up to fight at Carcemish on the Euphrates, and Josiah went out to meet him in battle. But Neco sent messengers to him, saying, “What quarrel is there between you and me, O King of Judag? It is not you I am attacking at this time, but the house with which I am at war. God has told me to hurry; so stop opposing God, who is with me, or he will destoy you.”

Josiah, however, would not turn away from him, but disguised himself to engage him in battle. He would not listen to what Neco had said at God’s command but went to fight him on the plain of Megiddo.

Archers shot King Josiah, and he told his officers, “Take me away; I am badly wounded.” So they took him out of his chariot, put him in the other chariot that he had and brought him to Jerusalem, where he died.

Did Josiah suffer defeat for opposing God?

That appears to be an open question, considering Josiah’s piety and Neco’s arrogance in claiming to speak for God. Neco lied, and the last of the Assyrians, weakened as they were, soundly defeated Neco in  battle at Carcemish. Nebuchadrezzar of Babylon subsequently demolished the Assyrians and set about appropriating their former dominions, including Judah.

Devout as Josiah was, I would like to think that he followed Hezekiah’s example in consulting God about what to do about the Egyptians. Considering his family history, it’s not improbable that he acted in haste and vanity.

Josiah certainly knew Neco lied. Perhaps Josiah recognized God’s hand in the downfall of the Assyrians brief rise of the Babylonian Empire and hoped to ally himself with them. However, he simply lacked the means and tactical skill to fight the Egyptians on their own terms and would have been better advised to use guerilla tactics in the hill country as opportunities arose.

Whatever the case, Josiah’s defeat at Megiido broght about the occupation and eventual obliteration of Jerusalem and Judah.

Josiah’s batlle was not the last to be fought on the plains of Megiddo, but it and earlier battles provided the prototype for later prophecies of a final day of reckoning in a climactic battle at Armageddon.

Jeremiah composed laments for Josiah, … These became a tradition in Israel …