July 3, and 4, 1863 were horrible days for the Confederacy because Lee was defeated at Gettysburg on the 3rd and Vicksburg fell to Grant on the 4th. Actually in my view Vicksburg was a more decisive victory for the Union than Gettysburg. Union farmers and manufacturers had suffered economic hardship early in the war because they couldn't get their goods to market using the Mississippi river. This contributed to anti-war sentiment in the mid-west and was beneficial to the Southern war effort. Secondly after Vicksburg fell the South was unable to move large quantities of men, supplies, and food across the river from Louisiana, Arkansas and Texas. People considered the Mississippi the spine of America. When Lincoln heard the joyful news about Vicksburg he sighed "Thank God" "The Father of waters again goes unvexed to the sea".