The Battle of Avaí was fought by the stream of the same name in Paraguayan territory in December 1868 during the Paraguayan War, between the forces the Triple Alliance and the Paraguay. It was one of the battles fought during the conflict known as December, when it recorded a series of victories achieved by Caxias in that month, to move toward the south to take Piquissiri behind, namely: the battles of Itororó, Avai, Valentinas Lomas and Angostura.