Nephite refugees from the city of Nephihah "came even and joined the army of Moroni" (Alma 59:8) which army presumably, according to Alma 59:5 was making preparations to go against the city of Morianton.
Geographical Theory Map: Alma 59:1-8 The Lamanites Take the City of Nephihah (30th Year)
Geographical [Theory Map]: Alma 59:8-11 The Nephites Flee to the Army of Moroni (30th Year)