Alma 49:13

for they knew not that Moroni had fortified or had built forts of security for every city in all the land round about; therefore they marched forward to the land of Noah, with a firm determination; yea, their Chief Captains came forward, and took an oath that they would destroy the people of that city.

They did not know that Moroni had built strong forts for every city in all the land around. So they marched forward to the land of Noah, determined to succeed. Their captains came forward and promised that they would destroy the people of that city.

They had no idea Moroni had fortified every single city in the region. They pressed on toward Noah with fierce determination. Their commanders even swore an oath to destroy everyone in that city.