Mormon's statement that the people of Limhi "laid wait for [the Lamanites] in the fields and in the forests" (Mosiah 20:8) seems to imply that fields and forests were on the route the Lamanites had to take from the land of Shemlon in order to get to the local land of Nephi. This is compatible with the proposed mountain valley setting of the land of Nephi.
Limhi could see the Lamanites from a tower, so they were not far away. So how long would it have taken the Lamanites to prepare for war and march the distance from the land of Shemlon to Lehi-Nephi in comparison to the time it would have taken Limhi to gather all his people and place them strategically in the fields and in the forests with specific instructions on battle tactics? The preparation that Limhi observed might have taken place over a period of days. Additionally, the apparent lack of Lamanite towers equivalent to those of the Nephites (a reasonable assumption if the land of Shemlon was lower than the land of Nephi) would leave the Lamanites without knowledge of the locations of Limhi's people. [Alan C. Miner, Personal Notes]
Geographical [Theory Map]: Mosiah 20:6-26 Lamanites Invade Nephi from Shemlon (Year 464)
Mosiah 20:10 They fought like lions ([Illustration]): The jaguar in the wild is still greatly feared wherever it is found in the lower forestlands of Mesoamerica. [John L. Sorenson, Images of Ancient America, p. 184]