Grierson's Raid was a Union cavalry raid during the Vicksburg Campaign of the American Civil War. It ran from April 17, to May 2, 1863, as a diversion from Ulysses S. Grant's main attack plan on Vicksburg, Mississippi.

Up until this time in the war, Confederate cavalry commanders such as Nathan Bedford Forrest, John Hunt Morgan, and J.E.B. Stuart had ridden circles around the Union (literally, in Stuart's case; see the Peninsula Campaign), and it was time to out-do the Confederates in cavalry expeditions. The task fell to Colonel Benjamin Grierson, who, oddly, hated horses.

Grierson and his 1,700 horse troopers rode over six hundred miles through hostile territory (from southern Tennessee, through the state of Mississippi and to Union-held Baton Rouge, Louisiana), over routes no Union soldier had traveled before. They tore up railroads and burned crossties, freed slaves, burned Confederate storehouses, destroyed locomotives and commissary stores, ripped up bridges and trestles, burned buildings, and inflicted ten times the casualties they received, all while detachments of his troops made feints confusing the Confederates as to his actual whereabouts and direction.

Confederate General John C. Pemberton, commander of the Vicksburg garrison, was short on cavalry and could do nothing to Grierson. An entire division of Pemberton's soldiers was tied up defending the Vicksburg-Jackson railroad from the slippery Grierson, and consequently did nothing to stop Grant's landing on the east bank of the Mississippi below the city. The premier Confederate cavalry commander, Nathan Bedford Forrest, was off chasing another Union raider named Abel Streight in Alabama, and did nothing to stop Grierson.

While Streight's raid failed, occupying the deadly Forrest probably ensured the success of Grierson's Raid. Of course every Confederate in the state—save perhaps Forrest—was hot on Grierson's trail. All they gained was mass confusion. Grierson and his troopers ultimately pulled in to Baton Rouge; combined with Sherman's feint, the befuddled Confederates did not oppose Grant's landing on the east side of the Mississippi.

Grierson's Raid in Hollywood

The movie The Horse Soldiers, directed by John Ford, and starring John Wayne and William Holden, is loosely based on Grierson's Raid.