Compare and contrast three Civil War battles in 1863: Gettysburg, Vicksburg, and Chattanooga. Which of these three was more of a turning point in the Civil War?

All three of these battles were Union victories during the American Civil War. The Siege of Vicksburg spelled disaster when Ulysses S. Grant attacked the Confederate stronghold in Western Mississippi. Grant sent gunboats down the Mississippi River in order to choke the troops holed up in Vicksburg from their sources of food and ammunition in Jackson, Mississippi, which the general captured in 1863. By effectively starving out the troops at Vicksburg, Grant was able to cut the Confederate army in two by holding the Mississippi River. To relieve the pressure on Vicksburg, the Confederate general Robert E. Lee decided to take the fight to a Union city in the North to convince public opinion to end the war. More by luck than by design, the Confederates found themselves fighting against Union soldiers in Gettysburg, Pennsylvania. Lee put all of his eggs in one basket, so to speak, when he ordered one massive assault on the Union fortification at Cemetery Ridge. The result was a bloodbath, and hundreds of Lee's and Confederate general George Pickett’s men were cut down as they charged uphill in the open field against the Union encampment. The loss effectively wiped out Pickett’s entire division, and Vicksburg still had not been relieved. By July 4, 1863, the Confederates had fully occupied Vicksburg and controlled the Mississippi River, in large part because of the Gettysburg debacle. The third great Union victory took place in September of that same year in Chattanooga, which sat at a railhead of eastern Tennessee just north of the entry into Georgia. Though the Union soldiers were outnumbered by almost 15,000 men, they were able to occupy the city and prevent a Confederate counter-invasion. Demoralized and weakened by their lack of supply, the Confederate army retreated into southern Georgia, and the Civil War had all but been concluded.
Though it is a subjective question, I would argue that the Battle of Vicksburg was the most significant Union victory of the war. Grant’s success in both cutting the Confederate army in two and choking out the movement of supplies from Mississippi was paramount in precipitating Lee’s desperate attempt to eke out a victory at Gettysburg. A weakened, poorly supplied, and reduced Confederate force at Chattanooga similarly faced odds much worse than might have been the case if it were not for Grant's capture of Vicksburg. Therefore, it seems that the latter two battles owed much of their successful circumstances to this initial Union victory.