Philip Henry Sheridan (1831-88) was an aggressive Union general during the American Civil War (1861-65). He demonstrated his capacity for command during assignments on the U.S. frontier and in early Civil War operations. When General Ulysses S. Grant assumed command of all Union armies in early 1864, he chose Sheridan as his new cavalry commander. Sheridan’s successful Shenandoah Valley Campaign in 1864 crushed Confederate General Jubal Early’s cavalry while destroying much of the South’s food supply. Sheridan was instrumental in General Robert E. Lee’s withdrawal from Petersburg, Virginia, after which Lee would soon surrender to Grant in April 1865 and effectively end the war.