Alongside Ulysses S. Grant and William Tecumseh Sherman, Philip H. Sheridan is the least known of the triumvirate of generals most responsible for winning the Civil War. Yet, before Sherman's famous march through Georgia, it was General Sheridan who introduced scorched-earth warfare to the South, and it was his Cavalry Corps that compelled Robert E. Lee's surrender at Appomattox Courthouse. Sheridan's innovative cavalry tactics and "total war" strategy became staples of twentieth-century warfare.

After the war, Sheridan ruthlessly suppressed the raiding Plains Indians much as he had the Confederates, by killing warriors and burning villages, but he also defended reservation Indians from corrupt agents and contractors. Sheridan, an enthusiastic hunter and conservationist, later ordered the US cavalry to occupy and operate Yellowstone National Park to safeguard it from commercial exploitation.