Alma 53:16

But behold, it came to pass they had many sons, which had not entered into a covenant that they would not take their weapons of war to defend themselves against their enemies; therefore they did assemble themselves together at this time, as many as were able to take up arms; and they called themselves Nephites;

But they had many sons. Their sons had not made a promise not to fight their enemies. So they came together at this time. All who could pick up weapons came. They called themselves Nephites.

But here’s what happened: they had many sons who had never made that covenant. These young men had never promised not to take up weapons to defend themselves. So they gathered together—as many as were old enough to bear arms—and they called themselves Nephites.