Why were the siege of vicksburg and the battle of gettysburg crucial to the outcome of the war?

Vicksburg--cut the South in half
Gettysburg--morale victory for the North. 

The Battle of Vicksburg allowed for the Union to take hold of a crucial point on the Mississippi and cut the western portions of the Confederacy off from the rest. 

The Battle of Gettysburg provided a morale boost for the North and following came the Gettysburg address which set the tone for the war and motivated Union soldiers to continue.