Jehoahaz was twenty-three years old when he began to reign, and he reigned three months in Jerusalem.
The destruction of Judah and Jerusalem is here coming on by degrees. God so ordered it to show that he has no pleasure in the ruin of sinners, but had rather they would turn and live, and therefore gives them both time and inducement to repent and waits to be gracious. The history of these reigns was more largely recorded in the last three chapters of the second of Kings.
Commenting on 2 Chronicles 36:1-10
he reigned three months in Jerusalem--His possession of sovereign power was of but very brief duration; for Necho determined to follow up the advantage he had gained in Judah; and, deeming it expedient to have a king of his own nomination on the throne of that country, he deposed the popularly elected monarch and placed his brother Eliakim or Jehoiakim on the throne, whom he...
Jehoahaz [was] twenty and three years old when he began to reign, and he reigned three months in Jerusalem. (a) Three months after the death of Josiah, Necho came to Jerusalem, and so the plagues began, which Huldah and the prophets forewarned would come on Jerusalem.