First organized as the Department of the Shenandoah in 1861 and then disbanded in early 1862, the army became most effective after its recreation on August 1, 1864 under the command of Philip Sheridan.
The First and Second Cavalry Divisions were commanded by Brigadier Generals Julius Stahel (succeeded by Alfred N. Duffie) and William W. Averell respectively.
[4] The force was next created by order of Ulysses S. Grant on August 1, 1864, in response to a raid by Jubal Early and his Confederate army of 15,000 on Washington, D.C., and especially his defeat of Lew Wallace at the Battle of Monocacy Junction.
It was placed under Sheridan's command with orders to repel Early, deal with Confederate guerillas, and press on into the Shenandoah Valley in Virginia.
By the end of these battles, Early's force was effectively out of the war, and Sheridan proceeded with his secondary orders to destroy the ability of the Shenandoah Valley to produce foodstuffs for the Confederacy, torching farms and more than 2,000 mills.
Following those battles in the fall of 1864, the majority of the Army of the Shenandoah was detached to Grant at Petersburg and to William Tecumseh Sherman in Georgia.