This article addresses growing calls for a fifth debate on international relations’ (IR) “race amnesia.” The central argument is two-fold. First, contrary to conventional wisdom, racial justice was not omitted in “orthodox” scholarship—in particular Morgenthau’s realism. On the contrary, classical realists repeatedly critiqued the lack of racial justice throughout their careers. Second, racial justice was not only a concern for Morgenthau but also integral to his conception of the national interest, particularly in the Vietnam War. To Morgenthau, the national interest failed in Vietnam because the United States failed to define its purpose at home. Fundamental to its purpose was the question of racial justice. Morgenthau’s conception of the national interest has an enduring impact on contemporary realist scholarship. This scholarship engages with issues that are relevant to postcolonial IR, such as the pursuit of primacy in the War on Terror, the backlash in the form of Trumpism, and the Black Lives Matter protests. Morgenthau’s work provides the intellectual roots that sustain these arguments. For a fifth debate on race in IR to materialize, it is thus this neglected dimension in Morgenthau’s writing that postcolonial scholarship needs to engage with.