In the aftermath of the battle, the bodies of the Lamanites were cast into the Sidon. This was a sign of disrespect for an enemy. Although it does not say so here, the Nephite dead were surely buried.
When the war is over, the Nephite armies “returned and came to their houses and their lands.” This was not a standing army, but one recruited from the men of the land. We see neither standing armies nor dedicated police forces in the Book of Mormon.
With the ending of the record of the eighteenth year of the reign of the judges, Alma stops recording. The story of what happens to Alma will be told in the next chapter, one written by Helaman rather than Alma.