This article re-examines Vietnamese diasporic anticommunism in the context of twentieth-century Vietnamese history. It offers an overview of the Vietnamese anticommunist tradition from colonialism to the end of the Vietnam War, and interprets the effects of national loss and incarceration on South Vietnamese anticommunists. These experiences contributed to an essentialization of anticommunism among the prisoners, who eventually provided a critical mass for anticommunist activism in the United States since the early 1990s.