Mosiah 21:20

And he caused that his people should watch the land round about, that by some means they might take those priests that fled into the wilderness, which had stolen the daughters of the Lamanites, and that had caused such a great destruction to come upon them;

He had his people watch the land all around. They hoped to catch those priests who had run into the wilderness. Those priests had stolen the daughters of the Lamanites. They had caused so much trouble to come upon them.

He ordered his people to watch the surrounding land, hoping to catch the priests who had fled into the wilderness—the ones who had kidnapped the Lamanite daughters and brought such devastation.