Diversionary railroad raids exhausted General Grant’s repertoire when it came to cavalry. During the climax of the Vicksburg Campaign, as his infantry crossed the Mississippi below that Secessionist citadel, Grant had sent a brigade of horse soldiers southward from LaGrange, Tennessee through Mississippi to Baton Rouge, Louisiana, ripping up rails, burning cross-ties, breaking bridges, destroying enemy supplies, tying down enemy infantry in defense of the vital rail link between Vicksburg and Jackson, and generally confusing the Confederates. The raid thus contributed to Grant’s investment and capture of the Gibraltar of the West. During the Overland Campaign, the general-in-chief had dispatched Sheridan with three divisions of horsemen from Spotsylvania to defeat Maj. Gen. J. E. B. “Jeb” Stuart, disrupt the railroad lines supplying Lee’s army, and threaten Richmond. Sheridan accomplished little beyond defeating and killing Stuart, whom Lee ultimately replaced with a better cavalry commander—Hampton, the war’s best commander of an army’s cavalry corps.
By sending his cavalry off to divert his enemy’s attention by ripping up rails, Grant deprived himself of horsemen for screening and reconnaissance, their traditional functions. The principal value of Sheridan’s raids lay in that they forced Lee to dispatch his cavalry in pursuit. Unlike Grant, the Southern chieftain employed his horse soldiers extensively in reconnaissance and screening. For Lee, cavalry functioned as a sensory organ. The absence of most of Lee’s horsemen in pursuit of Sheridan on the Trevilian Raid left the Secessionist commander nearly blind and contributed to the success of Grant’s James crossing. Grant no sooner gave up his assaults on Petersburg in June 1864 than he launched what cavalry remained with him on a raid against the Weldon, South Side, and Danville railroads.
 The great film director John Ford made a movie based on Grierson’s raid, entitled The Horse Soldiers (1959).
 Though Nathan Bedford Forrest proved formidable in independent command, he performed poorly in command of part of the Army of Tennessee’s cavalry. David Powell, Failure in the Saddle: Nathan Bedford Forrest, Joseph Wheeler, and the Confederate Cavalry in the Chickamauga Campaign (El Dorado Hills, Ca., 2011), 205-212, 232-235.