Alma 49:1 - 49:5
Alma 49: 1 And now it came to pass in the eleventh month of the nineteenth year, on the tenth day of the month, the armies of the Lamanites were seen approaching towards the land of Ammonihah.
On the 10th day of the 11th month, the Lamanite army was spotted approaching the land of Ammonihah.
Alma 49: 2 And behold, the city had been rebuilt, and Moroni had stationed an army by the borders of the city, and they had cast up dirt round about to shield them from the arrows and the stones of the Lamanites; for behold, they fought with stones and with arrows.
Moroni had been working on the defenses of Ammonihah during the time of peace anticipating that this would be their first place to attacked and was ready for the Lamanites. He had piled up dirt to form high walls to shield his men from the stones and arrows that the Lamanites used as their primary weapons.
Alma 49: 3 Behold, I said that the city of Ammonihah had been rebuilt. I say unto you, yea, that it was in part rebuilt; 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 not been completing rebuilt as the Lamanites had previously totally destroyed it because of the iniquity of its inhabitants. The Lamanites thinking it would be an easy target, attached it first.
Alma 49: 4 But behold, how great was their disappointment; for behold, the Nephites had dug up a ridge of earth round about them, which was so high that the Lamanites could not cast their stones and their arrows at them that they might take effect, neither could they come upon them save it was by their place of entrance.
However, when the Lamanites approached they were surprised by the high walls around Moroni’s defenses. With the high walls of dirt, the Lamanite stones and arrows would have little effect. The only way to get to the Moroni’s men was through an entrance that was heavy defended.
Alma 49: 5 Now at this time the chief captains of the Lamanites were astonished exceedingly, because of the wisdom of the Nephites in preparing their places of security.
This fortification was a shock to the Lamanite commanders. They had never suspected that the Nephites would be ready for them or at the kind of defenses that had been created to oppose them.