The first two years of war were uncertain for cavalry. Grant had not decided how to organize horsemen. Western cavalry had no clear mission. Instead mounted troops performed many, varied services, recovered locomotives, built roads and got scattered into mere squads, subject to infantry officers.
In contrast, Union General Pope concentrated his cavalry into one division. That prompted General Grant to establish a cavalry division, commanded by Colonel Dickey, but nine days later Grant revoked the order and divided mounted troops between Colonel Lee of 7th Kansas, Edward Hatch 2nd Iowa, and Benjamin H. Grierson 6th Illinois. April 17, 1863 - Union Colonel Benjamin Grierson left La Grange, Tennessee with 1,700 cavalry troops on a mission to destroy enemy supplies, telegraph lines and railroads in Mississippi.
Colonel Grierson had orders to create a cavalry diversion. He and three regiments of cavalry, 1,700 men, plunged south through a gap in rebel lines, rampaging the heart of Mississippi, ripping up rails and tearing down telegraph lines. Their purpose—make Confederates wrestle with all sorts of dire possibilities. How well they disguised Grant’s intentions could make or break the Vicksburg offensive. The raid ended on May 2 when Grierson and his men rode into Union occupied Baton Rouge, Louisiana.