Alma 49:19 says that "the Nephites prepared to destroy all such as should attempt to climb up to enter the fort by any other way [other than the entrance] by casting over stones and arrows at them. According to the report "Defensive Earthworks at Becan, Campeche, Mexico, Implications for Maya Warfare" by David L. Webster: "The steep angles of the inner ditch wall and parapet slope could not have been climbed without the aid of ladders; an enemy force caught in the bottom of the ditch would have been at the mercy of the defenders, whose most effective weapons under the circumstances would have been large rocks." [Michael and June Hobby, Proofs of the Book of Mormon, p. 39]