What was the significance of the Confederate surrender at Vicksburg?

At the beginning of the Civil War the North implemented a plan to cut the Confederacy off from any outside supplies or support. The south was dependent on imports from Europe to augment its industrial output of military supplies. The south would export cotton and use the proceeds to purchase rifles, cannons, and military supplies.

The naval blockade of southern ports severely limited the export of cotton. However the Confederacy had accounts in banks in London and Paris that they could use to purchase military supplies even warships equipped in Europe to raid Northern shipping. The last remaining method for getting the desperately needed supplies was to ship the military equipment to neutral Mexico and then move the supplies across Texas and the Mississippi River.

With the fall of Vicksburg the control of the Mississippi River fell to the Union forces. The Confederacy could no longer get supplies across the Mississippi. The last route for getting supplies from outside to fight the war was closed. Without a source of outside supplies and reinforcements the Confederacy was doomed. The only hope left for the south was that the North would get tired of fighting and quit.

The fall of Vicksburg completed the encirclement of the Confederacy as envisioned in the Anaconda Plan. This cut the Confederacy off from all outside support and supply.