With Union armies poised to launch the final campaigns against the Confederacy in 1864, three of its five commanders were "political generals"--appointed officers with little or no military training. Army chief of staff Henry Halleck thought such generals jeopardized the lives of men under their command and he and his peers held them in utter contempt. Historians have largely followed suit.

Thomas Goss, however, offers a new and more positive assessment of the leadership qualities of these Northern commanders. In the process, he cuts through the stereotypes of political generals as...