Kammala jumla mai zuwa: López, yana gaskanta cewa zai iya ba da mummunan rauni ga Allies, ya kaddamar da babban hari tare da mutane 25,000 a kan sojojin Allied 35,000 a
Yaƙin Tuyutí a ranar 24 ga Mayu, 1866, ɗayan yaƙe-yaƙe mafi zub da jini a tarihin Latin Amurka. Duk da kasancewa kusa da nasara a Tuyuti, shirin López ya lalace saboda tsananin juriya na sojojin Allied da kuma yanke shawara na bindigogi na Brazil. Dukkanin bangarorin biyu sun sha wahala sosai: sama da mutane 12,000 na Paraguay da 6,000 na Allies.