Alma 46:31

therefore Moroni thought it was expedient that he should take his armies, which had gathered themselves together, and armed themselves, and entered into a covenant to keep the peace:—And it came to pass that he took his army, and marched out into the wilderness, to cut off the course of Amalickiah in the wilderness.

Moroni thought he should take his armies. They had come together, put on their armor, and made a promise to keep the peace. He took his army and marched into the wilderness to stop Amalickiah.

So Moroni took his army—the one that had gathered and armed itself and made a covenant to keep the peace—and marched into the wilderness to cut off Amalickiah’s escape route.