During the
Valley Campaigns of 1864, while General
Philip Sheridan drove up the
Shenandoah Valley he faced a significant threat to his rear and supply lines from Mosby's Rangers based east of the
Blue Ridge in Loudoun and Fauquier. Subsequently, he was forced to dedicate significant resources to protecting his rear. Furthermore, Mosby and other partisans in Loudoun routinely raided Union garrisons in
Fairfax County and along the
Potomac River in
Maryland. In order to limit this threat, General
Grant wrote to Sheridan on August 16 suggesting: If you can possibly spare a division of Cavalry, send them through Loudoun County and destroy and carry off all the crops, animals, negroes, and all men under fifty years of age capable of bearing arms. In this way you will get many of Mosby's men. All male citizens under fifty can be fairly held as prisoners of war, not as citizen prisoners. If not already soldiers, they will be made so the moment the rebel army gets hold of them. At the time, Sheridan was still battling
Jubal Early for control of the valley and could not spare a large force for the task. On the 20th he dispatched 650 troopers of the 8th Illinois Cavalry into Loudoun to "break up and exterminate any bands or parties of Mosby's Elijah V. White|[Elijah V.] White's, or other guerrillas which may be met", but the troopers were unable to find and capture the elusive partisans. The failure of Sheridan to deal with Mosby did not go unnoticed by Grant, who wrote him again on November 9, insisting: There is no doubt about the necessity of clearing out that country so it will not support Mosby's gang... So long as the war lasts they must be prevented from raising another crop. Though Sheridan had by then defeated Early's army in late October at the
Battle of Cedar Creek, he feared such action might agitate anti-war advocates and negatively impact the reelection of
Abraham Lincoln. In late November, with Lincoln's reelection assured, Sheridan decided he could finally safely conduct operations against Mosby. On the 26th he wrote Union Chief of Staff
Henry Halleck, likening his plans for Loudoun to The Burning of the Valley he was then conducting: Now there is going to be an intense hatred of [Mosby] in that portion of the Valley which is nearly desert. I will soon commence on Loudoun County, and let them know there is a God in Israel. The following day he ordered
Major General Wesley Merritt and his 1st Cavalry Division to Loudoun: You are hereby directed to proceed, to-morrow morning at 7 o'clock, with the two brigades of your division now in camp, to the east side of the Blue Ridge, via Ashby's Gap, and operate against the guerrillas in the district of country bounded on the south by the line of the Manassas Gap Railroad as far east as White Plains, on the east by the Bull Run Range, on the west by the Shenandoah River, and on the north by the Potomac... To clear the country of these parties that are bringing destruction upon the innocent, as well as their guilty supporters, by their cowardly acts, you will consume and destroy all forage and subsistence, burn all barns and mills and their contents, and drive off all livestock in the region, the boundaries of which are described above. This order must be literally executed, bearing in mind, however, that no dwellings are to be burned and that no personal violence be offered the citizens... ==The raid==