Alma 58:3

Yea, and it became expdient that we should employ our men, to the maintaining those parts of the land, of the which we had retained of our possessions; therefore it became expedient that we should wait, that we might receive more strength from the land of Zarahemla, and also a new supply of provisions.

We needed to use our men to keep the land we still had. So we had to wait to get more soldiers from the land of Zarahemla. We also needed more food.

We had to use our soldiers just to hold onto the territory we’d already reclaimed. So we decided to wait for reinforcements and fresh supplies from Zarahemla.