The Zoramites were angry with the Nephites for taking in their refugees. They joined the Lamanites and then—together with the Amulonites and the wicked and murderous Amalekites—they mustered their armies of thousands to attack the Nephites. They were all under the command of the Lamanite leader Zerahemnah who hoped to conquer the Nephites and put them in slavery.
While the soldiers of the Lamanite army greatly outnumbered their enemy, they were naked save for a loin cloth, and they became afraid to attack when they saw that the Nephites had mustered to defend themselves clad in breast plates, helmets, arm-shields, and thick clothing. Leading the Nephites was a 25-year-old captain named Moroni.
So instead of a direct attack, the Lamanites fell back and then attempted to maneuver around Moroni's army to attack a more poorly defended area. But Jesus informed Alma the Younger of their intentions, and Alma passed this on to Moroni, and Moroni was able to split his army up and surround the Lamanites. The work of death commenced and it was more dreadful for the Lamanites who had no protection from the blows of the Nephite swords that brought death at almost every stroke.
When the Lamanites realized they were surrounded on all sides, they began fighting with extreme strength and courage—greater than any ever known. They were inspired by the Zoramites and Amalekites who had been made officers over them, and who fought like dragons, killing many Nephites, even cutting their helmets in half and chopping off many of their arms in their fierce anger.
In the face of such fierceness and anger, the Nephites thought to flee, but Moroni sensed this and inspired them, reminding them that they were fighting for their lands, their families, their liberty, and their religion. The Nephites then cried out in unison to Jesus their God for liberty and freedom from slavery. And the Lamanites, despite outnumbering them two-to-one, began to flee.
But the Lamanites were fully encircled and could not escape. They became struck with terror, and when Moroni saw this, he commanded his men to stop the bloodshed. "Jesus is supporting us because of our faith, and will not allow us to be destroyed," Moroni announced to the Lamanites, "Drop you weapons and vow never to attack us again, and we will spare your lives."
Zerahemnah came forward, dropped his weapons, and said, "We are not of your religion and do not believe that God caused you to defeat us. It was your cunning, and your breastplates and shields. Furthermore, we will not make a vow to you that we know we and our children would only break." So Moroni returned to him his weapons, saying, "Then we will end this conflict."
When Zerahemnah was given back his sword, he rushed at Moroni, but one of the Nephite soldiers raised his sword and broke the Lamanite leader's sword at the hilt. This same soldier then cut off Zerahemnah's scalp and held it aloft at the end of his sword. At this, many of the Lamanites put down their weapons, made the vow of peace, and departed.
Now Zerahemnah was furious and stirred his remaining men to anger, ordering them to attack the Nephites. Moroni was angry at the stubbornness of the Lamanites and ordered his men to kill them, and the nearly-naked Lamanites were cut down very quickly. Finally when Zerahemnah saw that they were about to be completely wiped out, he pleaded for Moroni to spare them, and he vowed not to attack the Nephites ever again.
Moroni allowed the surviving Lamanites to depart after disarming themselves, and then he and his men threw the bodies of all the dead into the river Sidon which carried them out to sea. Then the armies of the Nephites returned to their homes.