This thesis situates the presidency of Ulysses S. Grant (1869-1877) and the attempts to provide him with a third term in the republican political culture of Reconstruction. Exploring the period through the lens of the press, pamphlets, and archival material, it shows how republican ideas – especially hostility to partisan politics and fear of concentrated power – in the era had the capacity to both augment and detract from the president's ability to secure the post-war settlement. Early interpretations of Grant's presidency, written by scholars often hostile to Reconstruction, accused him of overzealous support for African-American civil rights. In contrast, revisionists blamed Reconstruction's failure in part on Grant's weak administration. However, when viewed through the prism of the republican political culture of the era, it is possible to see how Grant's presidency could be simultaneously strong and weak. Republicanism enabled the portrayal of Grant as both a model republican and a tyrantin-waiting. This thesis argues that the very qualities which made him a strong president – his antipartisanship, self-sacrifice, and honour – gave Grant the independence and support which many feared would be the undoing of the republic. Republicanism had the power to define the parameters of the possible during Reconstruction. With the federal government in tumult and the boundaries of presidential power undefined, Americans' fears over the safety of their liberties helped shape what could be achieved during Reconstruction. When Grant and his backers were able to portray the General as a model republican they helped to increase his political capital. But by painting Grant as a tyrant, political figures – beginning with his opponents and ending with his supporters – undermined his political capital to protect the fragile gains of Reconstruction. This thesis, by exploring several moments before, during, and after Grant's presidency in which the question of presidential power came to the fore argues that a political culture shaped by republicanism contributed to the downfall of Reconstruction.