Alma 49:3

Behold, I said that the city of Ammonihah had been re-built. I say unto you, yea, that it was in part re-built, and because the Lamanites had destroyed it once because of the iniquity of the people, they supposed that it would again become an easy prey for them.

The city of Ammonihah had been partly rebuilt. The Lamanites had destroyed it once because the people were wicked. So they thought it would be easy to conquer again.

Now, I should clarify: the city was only partially rebuilt. The Lamanites had destroyed it once before because of the people’s wickedness, so they figured it would be easy pickings again.