In his Vicksburg campaign of 1862-63 to control the Mississippi river which was the main river transportation route of the confederacy. Capture meant the confederates would be split in 2 as Vicksburg was an area on the river. Used steamboats to supply the army and move troops- it could carry 500 tons of supplies enough to feed 40,000 troops and 18,000 horses for 2 days. He used them to overcome the strong fortification by surrounding and sieging the city until the force of 35,000 confederates surrendered