The battle and siege of Vicksburg had a significant effect on the outcome of the Civil War. After failed direct attacks, General Grant surrounded Vicksburg and initiated a siege. After 45 days with no relief from other Confederate troops, General Pemberton surrendered the city on July 3rd, giving the Union control over the Mississippi River and cutting off Confederate states west of it from support and supplies. The dual victories at Vicksburg and Gettysburg were major boosts for the Union war effort.