As part of Moroni's defensive scheme, the Nephite lands were apparently viewed as being divided into quarters. There are two distinct phrases used overwhelmingly during the tenure of Moroni as chief commander of the Nephites. The first phrase is "that quarter of the land" (see Alma 43:26; 52:10; 56:1; 58:30; 58:35). The second phrase is "that part of the land" (see Alma 23:14; 49:15; 50:26; 52:13; 53:8; 56:2,9; 59:3,6; 61:6,15; 62:12). [Alan C. Miner, Personal Notes] [See the commentary on Alma 52:10]
Geographical Theory Map: Alma 43:25 Nephites Go to Land of Manti (18th Year)
“Moroni Caused That All the People in That Quarter of the Land Should Gather Themselves Together to Battle Against the Lamanites”
Brant Gardner notes that Moroni is captain of an army that has already been assembled in the east wilderness. When he arrives in Manti he requests another army. He requests that the people "in that quarter of the land" participate in their own defense and "gather themselves together to battle against the Lamanites" (Alma 43:26)
This is a very standard means of raising an army in Mesoamerica. There may have been those who were trained militarily, but the larger part of the army was raised from the people of the land. This description of the recruitment of a local militia is quite appropriate for the Mesoamerican context in which we are placing the Book of Mormon. [Brant Gardner, Book of Mormon Commentary, [http://www.highfiber.com/] ~nahualli/LDStopics/Alma/Alma43.htm, p. 17]