The hill Riplah was a height near the east bank of the river Sidon, by the borders of the land of Manti, where Moroni met a Lamanite army under Zerahemnah. Having learned the Lamanites’ line of march, Moroni divided his army and concealed part of it on the east and south of the hill Riplah, with the remainder hidden in the valley west of the river Sidon (Alma 43:31).
The Lamanites came up on the north of the hill, and as they passed Riplah and began to cross the river Sidon, the force concealed on the south, led by Lehi, came out and encircled them in their rear (Alma 43:33-36). The fighting drove the Lamanites across the river, where Moroni’s army met them, and the Lamanites were surrounded on both sides of the Sidon. When Zerahemnah saw his army about to be destroyed, he asked to make a covenant that his people would never again make war on the Nephites; Moroni stopped the killing, took their weapons, and let them depart into the wilderness (Alma 44:20).