Alma 27:2

And it came to pass that the Amalekites, because of their loss, were exceeding angry. And when they saw that they could not seek revenge from the Nephites, they began to stir up the people in anger against their brethren, the people of Anti-Nephi-Lehi; therefore they began again to destroy them.

The Amalekites were very angry because they lost. They could not get revenge on the Nephites. So they started making the people angry at their relatives, the people of Anti-Nephi-Lehi. They began to kill them again.

The Amalekites were furious about their losses. When they couldn’t get revenge on the Nephites, they turned their rage toward their own people—the Anti-Nephi-Lehies. They began attacking them instead.