The meaning of the Civil War, America’s most violent experience, continued to be debated well into the Gilded Age and Progressive Era. The long shadow cast by David Blight’s influential Race and Reunion: The Civil War in American Memory (2001) has meant that debates about the impact and prevalence of reconciliationist rhetoric dominate the literature. This paper adds to a growing body of scholarship that questions the reconciliationist narrative and stresses instead the partisan understanding of the Civil War still prevalent into the twentieth century. In particular, this article uses Theodore Roosevelt’s “memory” of the Civil War to explore the linkages between the Civil War Era and the Age of Empire. It makes two arguments: 1) that in an era when a “reconciliationist” understanding of the Civil War was becoming more prominent, more often than not Roosevelt used his voice as a historian and political figure to assert a “Unionist” interpretation; and 2) that Roosevelt used this memory of the Civil War to advocate for three specific political causes: American empire, the New Nationalism, and American entry into World War I. The paper’s argument and historiographical intervention help scholars of the Gilded Age and Progressive Era to re-imagine the role of Civil War memory in the half century following Appomattox Courthouse.