The Warrenton Junction Raid (May 3, 1863) was a surprise attack by Confederate guerrilla warriors on a Union cavalry detachment during the American Civil War.

The raid took place near a railroad junction in Virginia's Fauquier County, less than 10 miles (16 km) from the town of Warrenton.

Confederate Major (eventually Colonel) John S. Mosby led the attack against about 100 men from the Union's 1st (West) Virginia Cavalry.

As Mosby's men rounded up prisoners and horses, a detachment of the 5th New York Cavalry surprised the rebels and rescued most of the captured Union soldiers.

After a short fight, more men from the 5th New York, and the 1st Vermont Cavalry, joined in the pursuit of Mosby's fleeing rebels.

Casualties for the detachment of the 1st (West) Virginia Cavalry, the unit surprised by Mosby, totaled 16 men.

Although Mosby was forced to release most of his prisoners while escaping from the 5th New York Cavalry, he still managed to keep at least two West Virginians in captivity.

The Confederacy's Mosby's Rangers suffered their first defeat, but became masters of guerrilla warfare and were a constant concern for Union armies in eastern Virginia.

[Note 1] Because of the county's location and the presence of a railroad, troops for both sides in the American Civil War were often nearby.

[5] The Orange and Alexandria Railroad, which ran through the county, had strategic significance because it was part of the only rail link between Washington and Richmond.

This branch line, which was completed by the 1850s, helped the town thrive as farmers brought crops and livestock for sale and distribution.

[9] In early 1863, Confederate generals Robert E. Lee and James Ewell Brown "Jeb" Stuart gave permission for John Singleton Mosby to lead a group of 15 partisan rangers that would operate within enemy lines in northern Virginia.

Mosby patterned his technique after General Francis Marion, a leader in the American Revolutionary War who learned his fighting style from the Cherokee Indians.

His Mosby's Rangers operated primarily in a region surrounding Warrenton that included Clarke, Fauquier, Loudoun, Prince William, and Warren counties.

[15] On May 2, Mosby assembled a group of 70 to 100 men for the purpose of attacking the supply wagons of Union General Joseph Hooker's army.

One Ohio soldier, writing about some fighting that occurred in early 1862, said that the 1st (West) Virginia Cavalry's original regiment commander "was one of the foreign adventurers who so largely officered our army at its beginning and were absolutely useless for any purpose except to draw their pay and to wear gold braid.

"[24] Later in 1862, a report by Union General James Shields, sent to Secretary of War Edwin M. Stanton, said "First Virginia Cavalry good for nothing.

[Note 4] On May 3, 1863, the detachment was less than 60 miles (97 km) west of Washington, DC, near the junction of the Orange and Alexandria and Manassas Gap railroads.

[37] The surprised men from the 1st (West) Virginia Cavalry ran for their weapons and sought cover in three nearby buildings.

About 40 of the New Yorkers, led by Major John Hammond, quickly rode to the rescue of the West Virginians—arriving right after Mosby collected prisoners from the burning house.

"[33] Union General J.J. Abercrombie's report that said Mosby's "front rank was dressed in the uniform of United States soldiers".

During the spring after the Mosby encounter, the 1st (West) Virginia Cavalry Regiment became armed with Spencer repeating rifles.

[44] Officers from the regiment sent a petition to Secretary of War Stanton to have their well-thought-of second permanent commander, Lieutenant Colonel Nathaniel P. Richmond, reinstated.

[22] All three Union cavalry regiments involved in the Warrenton Junction Raid (5th New York, 1st Vermont, 1st West Virginia) fought at the Battle of Gettysburg as part of the same brigade.

During that pursuit, the 1st West Virginia Cavalry charged down a mountain and captured a Confederate artillery piece and an entire wagon train.

[52] In 1865, the 1st West Virginia Cavalry was in the Third Brigade of the Third Division of General Philip Sheridan's Army of the Shenandoah.

Abram Krom, a captain in the 5th New York Cavalry, became a major and briefly commanded the regiment in 1864 after Hammond left.

General Ulysses S. Grant narrowly escaped capture by Mosby's men, and decided to avoid traveling to Washington from his headquarters with the Army of the Potomac.

Retaliations and injustices occurred (depending on one's point of view), and Powell threatened to execute 22 prisoners for every one of his men he considered murdered by outlawed guerrillas.

[Note 10] After receiving a letter from Mosby, Sheridan agreed to a truce in the brutality committed by both sides against prisoners.