("Yah is strong") was King of Judah (798-769), the son of King Joash, and mother Jehoaddin, became king at age 25, and reigned 29 years. After becoming king, he killed the men who had assassinated his father. Amaziah assembled an army from Judah and Benjamin, and re-conquered Edom, which had gained its independence from Judah about 50 year's earlier.
Amaziah also had hired 100,000 men from Israel to participate in the battle, but gave up the idea in view of the opposition it aroused. He dismissed the men, but the soldiers were displeased and on their way home, raided several cities of Judah, killing 3000 people.
When King Amaziah returned from defeating the Edomites, he brought with him idols from Seir, set them up as gods, and bowed before them. This made the Lord angry and the Lord sent a prophet to warn him, Amaziah rebuked the prophet. He then declared war on King Joash of Israel. The Israelites defeated Judah, and King Amaziah was captured.
King Joash took many hostages, and all the gold and silver from the Temple and palace, and returned to Samaria. However Amaziah lived 15 years longer than Joash. Amaziah was assassinated by his enemies in Lachish. His body was returned to Jerusalem and buried in the Royal cemetery. His son Uzziah (also known as Azariah) became king.