Sheridan, Philip Henry (1831–1888), United States army officer. A daring and aggressive cavalry officer, “Little Phil,” as he was called by his men, was one of the most successful Union commanders in the Civil War.

Sheridan's Shenandoah Valley campaign of August, 1864 to March, 1865, resulted in the destruction of a Confederate army under General Jubal A. Early and the devastation of the valley, which had been a major Confederate supply source. It was during this campaign that Sheridan made a ride of 14 miles (22.3 km) from Winchester, Virginia, to Cedar Creek in the midst of battle to rally his faltering troops and personally lead them to victory. His drive southward to block Lee's withdrawal from Petersburg helped force the Confederate surrender at Appomattox Court House, April 9, 1865.

Sheridan was born in Albany, New York, the son of Irish immigrants. He spent his boyhood in Ohio and won appointment to the United States Military Academy. After his graduation in 1853, he served a a lieutenant of infantry in Texas and in campaigns against the Indians in the Northwest.

Sheridan was an infantry captain in Missouri at the outbreak of the Civil War. He held various administrative posts before being appointed a colonel of cavalry. After a victory at Booneville, Mississippi, in 1862, Sheridan was transferred to the Army of the Cumberland, where he won promotions to brigadier general and to major general. Sheridan's success at Chickamauga and Chattanooga in 1863 led General Grant to name him commander of cavalry for the Army of the Potomac. He held this post until given direction of the Army of the Shenandoah in August, 1864.

Following the war, Sheridan was named commander of the military district of the Gulf and military governor of Texas and Louisiana. He pursued such stern Reconstruction policies, however, that President Johnson transferred him to Missouri. There Sheridan launched military operations against hostile Indians and forced them to settle on reservations. In 1884 he succeeded General Sherman as commanding general of the U.S Army. Sheridan was made a full general in 1888. Also in that year his Personal Memoirs was published.