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 Col. Benjamin Grierson, a former music teacher who, oddly, hated horses after being kicked in the head by one as a child. Grierson's cavalry brigade consisted of the 6th and 7th Illinois and 2nd Iowa Cavalry regiments.
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. Total casualties for Grierson's Brigade were three killed, seven wounded, and nine missing. Five sick and wounded men were left behind along the route, too ill to continue.
Confederate Lt. Gen. 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 evasive 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, Maj. Gen. Nathan Bedford Forrest, was off chasing another Union raider named Col. Abel Streight in Alabama, and did nothing to stop Grierson.
While Streight's Raid failed, occupying Forrest probably ensured the success of Grierson's Raid. Although many Confederates other than Forrest pursued Grierson vigorously across the state, all they gained was mass confusion. Grierson and his troopers ultimately pulled in to Baton Rouge, Louisiana; combined with Maj. Gen. William T. Sherman's feint northeast of Vicksburg (the Battle of Snyder's Bluff), the befuddled Confederates did not oppose Grant's landing on the east side of the Mississippi.