King Lamoni wanted to bring Ammon to meet his father who was king over all the Lamanites, but the voice of Jesus came to Ammon and warned him not to go and meet Lamoni's father, for the king of the Lamanites would try to kill him. He was instructed instead to go to the land of Middoni where his brother Aaron was being held in prison.
Lamoni insisted he accompany Ammon since the king of Middoni was a friend of his, and he could assist in getting Aaron out of prison. So they set off together in a chariot, but along the way they came across Lamoni's father. "Where are you going with this lying Nephite?" his father asked angrily. "The Nephites robbed our fathers, and look, they now seek to take our property again with their cunning lies!"
Lamoni told his father of their quest to free Aaron from Middoni, but his father forbade him to go to Middoni, and demanded that he kill Ammon with his sword. Lamoni refused to obey his father, and the angered king drew his sword to strike at his son. But Ammon protected Lamoni, using his sword to wound Lamoni’s father in the arm.
Lamoni's father pleaded for Ammon not to kill him, offering up to half his kingdom in return. Ammon said he would spare his life if he promised that his brother would be freed from prison, and also that Lamoni would remain a king and not be subject to his father's orders. Lamoni's father was astonished by Ammon, realizing that he did not intend to harm him and that he truly cared for his son. He became curious to learn the gospel that Ammon had taught his son.
Upon reaching Middoni, Lamoni arranged with the local king for Aaron to be released from prison. Aaron had suffered many days in prison, naked, hungry, and thirsty, and his skin was very worn where he had been tied up with ropes. They began to preach to the people and convinced many that they were sinners and that the traditions of their fathers were wrong.
Departing from Middoni, Ammon was called by the Spirit of the Lord to return to Lamoni's land and teach his people, while his brother Aaron was led by the Spirit to the palace of Lamoni's father in the city of Nephi. Aaron taught the king about the creation of Earth, the Plan of Salvation, and the atonement of Christ. The king believed his words, and his whole household was converted to Jesus.
The king issued a proclamation throughout his lands that Ammon and his brothers were not to be harmed as they preached throughout his lands, and that they were to be given free access to his people's houses, temples, and sanctuaries. And so the brothers traveled through the land establishing churches, ordaining priests and teachers, and they had great success. Thousands of Lamanites were brought the knowledge of Jesus and the traditions of the Nephites.
Just before the king died, he passed his kingdom on to Lamoni's brother, a convert named Anti-Nephi-Lehi. The converted Lamanites became known as Anti-Nephi-Lehies or Ammon's People. The new king convinced his people to give up their old ways. After repenting of all their killing, they buried their weapons deep underground and vowed to God never to kill again.
Now the Amulonites and Amalekites had not been converted, and they stirred up the unconverted Lamanites who lived among them to anger and convinced them to rebel against Anti-Nephi-Lehi their king. When these wicked Lamanites came to attack, Ammon's People went before them unarmed, knelt to the ground and called out to Jesus, more willing to be killed than to break their vow of pacifism.
And while they were knelt down and offering no resistance, the Amulonites, Amalekites, and Lamanites began to attack them, slaughtering them with their swords. Ammon's people did not flee or even attempt to avoid the blows of their attackers, and in this way more than one thousand of them were struck dead, praising God as they perished.
Eventually the attacking Lamanites began to feel compassion for their brothers who had converted, and they threw down their weapons. As many of them joined Ammon's People that day as had been slaughtered. But none of the Amulonites or Amalekites—whose ancestors were believing Nephites—were converted. And so we see that when a people knows the truth and falls into sin, their state is worse than if they had never known the truth to begin with.
The unconverted Amulonites, Amelekites, and Lamanites then took their armies to the land of the Nephites, and this is when the city of Ammonihah was completely annihilated, man, woman, and child. The Nephites then managed to drive these out these invaders. But once these Lamanites had been driven back into their own lands, they usurped power there, seized the Lamanites who had converted to Christianity, and began burning them at the stake.
Then Jesus instructed Ammon and his brothers to lead all of Ammon's People out of their homeland and into the land of the Nephites before they could be attacked again and slaughtered by the Amulonites, Amalekites, and unconverted Lamanites. And so the people were gathered and led into the wilderness, and Ammon and his brothers Aaron, Omner, and Himni rejoiced greatly over their success among the Lamanites.
As they approached the land of the Nephites they came across Alma the Younger and it was a joyful reunion. At Zarahemla, the chief judge consulted with the people and it was decided that Ammon's People would be given the land of Jershon, and the Nephites pledged to protect them so they could keep their vow of pacifism. Ammon's People became part of the Church of God and were perfectly honest and upright, and zealous in their faith.
Ammon's People had been followed through the wilderness by the armies of the unconverted Lamanites, and now they attacked, causing a tremendous slaughter among the Nephites. In what became the largest battle ever since Lehi and his family first left Jerusalem, the attacking Lamanites were driven away and scattered, and tens of thousands of Lamanites lay dead. It was an awful scene of bloodshed that left thousands mourning the dead.