At the time of the Civil War, the Mississippi River was the single most important economic feature of the continent — the very lifeblood of America. Upon the secession of the southern states, Confederate forces closed the river to navigation, which threatened to strangle northern commercial interests.
President Abraham Lincoln told his civilian and military leaders, "See what a lot of land these fellows hold, of which Vicksburg is the key! The war can never be brought to a close until that key is in our pocket...We can take all the northern ports of the Confederacy, and they can defy us from Vicksburg." Lincoln assured his listeners that "I am acquainted with that region and know what I am talking about, and as valuable as New Orleans will be to us, Vicksburg will be more so."
It was imperative for the administration in Washington to regain control of the lower Mississippi River, thereby opening that important avenue of commerce, and enabling the rich agricultural produce of the Northwest to reach world markets.
It would also split the South in two, sever a vital Confederate supply line, achieve a major objective of the Anaconda Plan, and effectively seal the doom of Richmond. In the spring of 1863, Major General Ulysses S. Grant launched his Union Army of the Tennessee on a campaign to pocket Vicksburg and provide Mr. Lincoln with the key to victory.