Alma 50:12

Thus Moroni, with his armies, which did increase daily, because of the assurance of protection which his works did bring forth unto them; therefore they did seek to cut off the strength and the power of the Lamanites, from off the lands of their possessions, that they should have no power upon the lands of their possession.

Moroni’s armies got bigger every day. The people felt safe because of the forts he built. So they tried to take away the power of the Lamanites from the land. They did not want the Lamanites to have any power over their land.

Moroni’s armies grew every day because people felt safe under his protection. They worked to cut off Lamanite strength and power, making sure the enemy had no foothold in Nephite territory.