The correct response is: General Lee's attempt to invade the North and win the war failed, which boosted Union troop's morale.
The Battle of Gettysburg (July 1-3, 1863) marked a significant turning point in the Civil War because it ended Lee's invasion of the North and resulted in a major defeat for the Confederacy. This victory for the Union not only halted Confederate momentum but also significantly increased morale among Union troops and supporters, which was crucial for sustaining efforts in the war. Although Lee wasn't removed from command as a direct result of this loss, the defeat contributed to the overall decline of Confederate military effectiveness in subsequent battles.