Jamieson, Fausset and Brown on 2 Kings 14:11-14

11-14. But Amaziah would not hear--The sarcastic tenor of this reply incited the king of Judah the more; for, being in a state of judicial blindness and infatuation (2Ch 25:20), he was immovably determined on war. But the superior energy of Joash surprised him ere he had completed his military preparations. Pouring a large army into the territory of Judah, he encountered Amaziah in a pitched battle, routed his army, and took him prisoner. Then having marched to Jerusalem [2Ki 14:13], he not only demolished part of the city walls, but plundered the treasures of the palace and temple. Taking hostages to prevent any further molestation from Judah, he terminated the war. Without leaving a garrison in Jerusalem, he returned to his capital with all convenient speed, his presence and all his forces being required to repel the troublesome incursions of the Syrians.

2Ki 14:17-20. He Is Slain by a Conspiracy.