(Ulysses S. Grant)
Up until the fall of Vicksburg, Robert E. Lee had been kicking some major Union ass and many in the north feared that the war was becoming a lost cause. In fact, In May of 1863, Abraham Lincoln received word that General Lee had achieved yet another victory at the Battle of Chancellorsville (which lasted from April 30th to May 6th). Lincoln paced around saying, "My God! My God! What will the country say? What will the country say?" When Lincoln left the Executive Mansion, a reporter named John Russell Young quoted Secretary of War Edwin Stanton saying, "Mr. Lincoln has fully made up his mind to go to the Potomac River and there end his life, as many a poor creature - but none half so miserable as he was at the time - had done before him." (Abraham Lincoln: The War Years by Carl Sandburg). But on May 18th, Grant began what has gone down in history as one of the most remarkable campaigns of the Civil War.
(Map of the Vicksburg Campaign. Click the image to enlarge it)
Vicksburg was an important river fortress/town for the Confederacy due to its prime location on the Mississippi river. Grant had been unable to capture the area since it was well protected by extremely dangerous terrain that had made his troops vulnerable to Confederate counter strikes led by John Pemberton. But although Grant had been beaten back in the past, he had no intention of that happening again.
(John Pemberton)
Instead of attempting to sail directly to Vicksburg, Grant sailed below it to Bruinsburgh where he surprised and overtook Joseph Johnston who was station with his troops in Jackson.
While marching toward Vicksburg, Union and Confederate troops met at Champion Hill. "The Hill of Death" would become the site of the bloodiest conflict in the Vicksburg campaign but Grant would emerge victorious and force the battered Confederates to retreat behind the walls of Vicksburg.
(Union forces pursuing retreating Confederates at the Battle of Champion Hill on May 16th)
After failing to attack Vicksburg head on, Grant decided that he would lose fewer men if he starved the fortress into surrender. Just as Lincoln had blockaded the South, Grant set up his own blockade around Vicksburg, bleeding dry the soldiers and civilians inside. 
(Grant can be seen in the lower right corner looking out over his entrenched troops toward Vicksburg)
After 47 days, Pemberton gave up his forces and allowed Grant, his troops, and much desired food and medical supplies to enter Vicksburg.
(Union troops-said to be the 4th Minnesota-entering Vicksburg in this painting by Francis Millet)
About 110,000 troops engaged in the campaign (77,000 Union and 33,000 Confederate). 806 Union soldiers died. 3,940 were wounded and 164 either went missing or were captured. 805 Confederates perished. 1,938 were killed and 29,620 went missing or were captured/surrender to Grant. (Figures from civilwar.org)
President Lincoln was thrilled to receive news of Grant's victory, especially so soon after the Battle of Gettysburg, and wrote to him a few days later.
My dear General
I do not remember that you and I ever met personally. I write this now as a grateful acknowledgment for the almost inestimable service you have done the country. I wish to say a word further. When you first reached the vicinity of Vicksburg, I thought you should do, what you finally did -- march the troops across the neck, run the batteries with the transports, and thus go below; and I never had any faith, except a general hope that you knew better than I, that the Yazoo Pass expedition, and the like, could succeed. When you got below, and took Port-Gibson, Grand Gulf, and vicinity, I thought you should go down the river and join Gen. Banks; and when you turned Northward East of the Big Black, I feared it was a mistake. I now wish to make the personal acknowledgment that you were right, and I was wrong.
Yours very truly
A. Lincoln
"With the Mississippi River now firmly in Union hands, the Confederacy's fate was all but sealed." (civilwar.org)
(Grant at Vicksburg)
May God bless America, from sea to shining sea, in the home of the free because of the brave.
Until next time.
XOXO, Kate
