Believing in the possibility of full citizenship and democratic change, W.E.B. Du Bois encouraged African Americans to support the Allied cause in World War I. For more than two decades afterward, Du Bois attempted to write the definitive history of Black participation in the war, but his book remained unfinished. As Chad Williams reveals, the story of this manuscript offers new insight into Du Bois's struggles to reckon with the troubling memory of the war, along with the broader meanings of race and democracy for Black people in the 20th century.