Amaziah was twenty-five years old when he became king, and he reigned in Jerusalem twenty-nine years. His mother was Jehoaddin, from Jerusalem.
Amaziah did what was pleasing in the LORD's sight, but not wholeheartedly.
When Amaziah was well established as king, he executed the men who had assassinated his father.
However, he did not kill the children of the assassins, for he obeyed the command of the LORD written in the Book of the Law of Moses: "Parents must not be put to death for the sins of their children, nor the children for the sins of their parents. Those worthy of death must be executed for their own crimes."
Another thing Amaziah did was to organize the army, assigning leaders to each clan from Judah and Benjamin. Then he took a census and found that he had an army of 300,000 men twenty years old and older, all trained in the use of spear and shield.
He also paid about 7,500 pounds of silver to hire 100,000 experienced fighting men from Israel.
But a man of God came to the king and said, "O king, do not hire troops from Israel, for the LORD is not with Israel. He will not help those people of Ephraim!
If you let them go with your troops into battle, you will be defeated no matter how well you fight. God will overthrow you, for he has the power to help or to frustrate."
Amaziah asked the man of God, "But what should I do about the silver I paid to hire the army of Israel?" The man of God replied, "The LORD is able to give you much more than this!"
So Amaziah discharged the hired troops and sent them back to Ephraim. This made them angry with Judah, and they returned home in a great rage.
Then Amaziah summoned his courage and led his army to the Valley of Salt, where they killed ten thousand Edomite troops from Seir.
They captured another ten thousand and took them to the top of a cliff and threw them off, dashing them to pieces on the rocks below.
Meanwhile, the hired troops that Amaziah had sent home raided several of the towns of Judah between Samaria and Beth-horon, killing three thousand people and carrying off great quantities of plunder.
When King Amaziah returned from defeating the Edomites, he brought with him idols taken from the people of Seir. He set them up as his own gods, bowed down in front of them, and presented sacrifices to them!
This made the LORD very angry, and he sent a prophet to ask, "Why have you worshiped gods who could not even save their own people from you?"
But the king interrupted him and said, "Since when have I asked your advice? Be quiet now before I have you killed!" So the prophet left with this warning: "I know that God has determined to destroy you because you have done this and have not accepted my counsel."
After consulting with his advisers, King Amaziah of Judah sent this challenge to Israel's king Jehoash, the son of Jehoahaz and grandson of Jehu: "Come and meet me in battle!"
But King Jehoash of Israel replied to King Amaziah of Judah with this story: "Out in the Lebanon mountains, a thistle sent a message to a mighty cedar tree: `Give your daughter in marriage to my son.' But just then a wild animal came by and stepped on the thistle, crushing it!
You may be very proud of your conquest of Edom, but my advice is to stay home. Why stir up trouble that will bring disaster on you and the people of Judah?"
But Amaziah would not listen, for God was arranging to destroy him for worshiping the gods of Edom.
So King Jehoash of Israel mobilized his army against King Amaziah of Judah. The two armies drew up their battle lines at Beth-shemesh in Judah.
Judah was routed by the army of Israel, and its army scattered and fled for home.
King Jehoash of Israel captured King Amaziah of Judah at Beth-shemesh and brought him back to Jerusalem. Then Jehoash ordered his army to demolish six hundred feet of Jerusalem's wall, from the Ephraim Gate to the Corner Gate.
He carried off all the gold and silver and all the utensils from the Temple of God that had been in the care of Obed-edom. He also seized the treasures of the royal palace, along with hostages, and then returned to Samaria.
King Amaziah of Judah lived on for fifteen years after the death of King Jehoash of Israel.
The rest of the events of Amaziah's reign, from beginning to end, are recorded in The Book of the Kings of Judah and Israel.
After Amaziah turned away from the LORD, there was a conspiracy against his life in Jerusalem, and he fled to Lachish. But his enemies sent assassins after him, and they killed him there.
They brought him back to Jerusalem on a horse, and he was buried with his ancestors in the City of David.