In BJ 4:286-288 Josephus is presenting an episode of the war: an inner-Jewish conflict between the people of Jerusalem and the Zealots. In this conflict the Idumeans join the party of the rebels. A stormy weather with earthquake is interpreted by both parties as a sign of an imminent action of God, who rescues Jerusalem and beats the enemies outside the city. The article argues for an interpretation of this theme on the background of the Zion-tradition with strong influences from the book of Isaiah (chap. 29 and 30).