King Hazael of Aram had defeated Israel during the reigns of Jehu and Jehoahaz (13:3, 22). He then pressed south along the Mediterranean coast toward Judah. He captured Gath (cf. 2 Chron. 11:8) and then sent soldiers against Jerusalem who killed many Judean leaders (2 Chron. 24:3). Rather than turning to Yahweh for deliverance, Jehoash bought Hazael off with gold from the renovated temple (2 Chron. 24:23).
The Arameans had wounded Jehoash who went to recuperate in a town named Beth Millo (2 Chron. 24:25). There several of his officials assassinated him (v. 20) primarily because he had slain the high priest Zechariah (2 Chron. 24:20-22). The king was buried in Jerusalem but not in the royal tombs (2 Chron. 24:25) because the people did not have great respect for him.
"Once a promising, God-fearing young ruler, Joash died a disappointment. By bribing Hazael with Temple treasures, he tarnished his one great achievement, the Temple restoration."78
Jehoash's reign started off well but ended poorly because he turned from Yahweh. Instead of continuing to follow the high priest's counsel, he silenced him by killing him. Consequently God's blessing on his earlier years in office turned into chastening later in his life.