General Philip Henry Sheridan (1831-1888) was the most important Union cavalry commander of the Civil War, and ranks as one of America's greatest horse soldiers. From Corinth through Chickamauga and Missionary Ridge, he made himself a reputation for courage and efficiency; after his defeat of J.E.B. Stuart's rebel cavalry, Grant named him commander of the Union forces in the Shenandoah Valley. There he laid waste to the entire region, and his victory...