On December 28, 1862, Sherman led thousands of men in an attack on the northeastern section of Vicksburg’s natural defenses. His assault, in the area known as the Chickasaw Bayou, was a complete disaster. Fortunately for the Union, Sherman was able to extricate his men after suffering almost 3,000 killed, wounded, or gone missing. There was, surprisingly, some benefit to the Northern cause: the defenders of Vicksburg became overconfident, even complacent, that winter.

Seeing the failure of a major assault, Grant decided on something much less dramatic. In February and March 1863, he had thousands of men wielding pickaxes and shovels, attempting to dig a new canal. The plan was to divert part of the flow of the Mississippi River away from Vicksburg and thereby make the approaches easier to handle. Given the enormous size of the great river, it seems incredible that Grant would devote such resources, but he had the full backing of Lincoln and the War Department. If there was a cheaper and easier way to take Vicksburg, official Washington was all for it.