How did the events at vicksburg change the tide of the war?

The win by the Union army at Vicksburg changed the tide of the war because it allowed the US to split the Confederacy in half. Thanks to this battle, the Union now controlled the Mississippi River. This river allowed the Confederates to move soldiers and supplies throughout the Confederacy. Now that the Union army controlled this river, they could not move troops or supplies to areas where they were needed.