Taste of Vengeance (1968)

Directed by Mario Siciliano

A group of Northern vigilantes, roaming the post Civil War south, attack and kill the fiancee of war veteran Brian, who is rescued by his friend, Daniel. The two, with brother Robert, set out to find the killers. But Brian, suffering from amnesia and becoming frustrated with not remembering the killer's faces, starts killing at random and loses the support of his two partners.