Final answer:
The Battle of Gettysburg was a turning point in the Civil War due to the prevention of the Confederate invasion, the heavy losses suffered by the Confederacy, and the shift in momentum in favor of the Union.
Step-by-step explanation:
The Battle of Gettysburg was a turning point in the Civil War for several reasons. First, it prevented General Robert E. Lee and the Confederate army from successfully invading the North. This marked the last offensive attempt by the Confederates and weakened their chances of foreign aid. Second, the Battle of Gettysburg resulted in heavy losses for the Confederate army, with more than a third of the Army of Northern Virginia being lost. This significant loss of manpower and resources hurt the Confederacy's ability to sustain the war. Finally, the Union victories at Gettysburg and Vicksburg (which happened on the same day) shifted the momentum in favor of the Union. With the Union controlling the Mississippi River and repelling the Confederate invasion, the Confederate forces lost their momentum, and the tide turned in favor of the Union in both the east and the west.