The Battle of Sipe-Sipe (also known as Battle of Viluma among Spanish historians) was a major battle in the South American wars of independence in which the United Provinces of Río de la Plata (formerly the Spanish Viceroyalty of the Río de la Plata) were decisively defeated by Spanish royalist forces in Upper Peru (now Bolivia). The battle took place on November 29, 1815, and resulted in the loss of Upper Peru for Buenos Aires. The area was reannexed by the Spanish Viceroyalty of Peru.