The Battle of Valdevez (Portuguese: Torneio de Arcos de Valdevez) took place at Arcos de Valdevez on the banks of the river Vez between the Kingdom of León and the Kingdom of Portugal in the summer of 1140 or 1141. It is one of only two pitched battles that Alfonso VII of León is known to have fought, and the only of the two not coincident with a siege. His opponent at Valdevez was his cousin Afonso I of Portugal. An armistice signed after the battle eventually became the Treaty of Zamora (1143), and ended Portugal's first war of independence. The area of the battle became known as the Veiga or Campo da Matança, the "field of killing".