Helaman 1:24

and supposing that their greatest strength was in the centre of the land, therefore he did march forth, giving them no time to assemble themselves together, save it were in small bodies; and in this manner they did fall upon them and cut them down to the earth.

He thought their strongest force was in the middle of the land. So he marched on. He gave them no time to gather together except in small groups. This way they attacked them and cut them down to the ground.

He figured the Nephites’ main strength was in the center of the land, so he kept moving fast, not giving them time to gather into large groups. He caught them in small bands and slaughtered them.