Three ex-Confederate officers were tried for war crimes in the aftermath of the American Civil War. These appear to be the first trials in modern history where a government tried officers of an enemy army for violating international customs of war. This thesis offers an integrative analysis of all three trial transcripts. By way of the transcripts and scholarship on the legal and political battles of early Reconstruction, the work clarifies what it was the prosecuting party was after and the extent to which the unfolding of the trials met or broke from their intentions. Doing so offers a strong indication of what allowed these unprecedented trials to take place; at the same time, it suggests what made the federal government abort its broader prosecutorial program after only three trials.