The Steele's Bayou Expedition was a joint operation of Major General Ulysses S. Grant's Army of the Tennessee and Rear Admiral David D. Porter's Mississippi River Squadron, conducted as a part of the Vicksburg Campaign of the American Civil War. Its aim was to move Union forces from the Mississippi River to a point on the Yazoo River upstream of Confederate Lieutenant General John C. Pemberton's defenses of Vicksburg.