2 Chronicles 35:16-20

So all the service of the Lord was prepared on that day to celebrate the Passover, and to offer burnt offerings on the altar of the Lord according to the command of King Josiah.

And the sons of Israel who were present celebrated the Passover at that time, and the Feast of Unleavened Bread for seven days.

There had not been a Passover celebrated like it in Israel since the days of Samuel the prophet; nor had any of the kings of Israel celebrated such a Passover as Josiah did with the priests, the Levites, all Judah and Israel who were present, and the inhabitants of Jerusalem.

In the eighteenth year of Josiah’s reign this Passover was celebrated. Josiah Dies in Battle

After all this, when Josiah had set the temple in order, Neco king of Egypt came up to wage war at Carchemish on the Euphrates, and Josiah went out to engage him.