At the time of the Civil War, the Mississippi River was the most important economic feature of the continent. When the Southern States succeeded, Confederate forces closed the river, which threatened to block northern commercial benefit.
President Abraham Lincoln told his civil 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". …
