Even if the Confederacy had won the battle of Gettysburg, it would not have changed the outcome of the Civil War. Though the spirits of the Union soldiers might have been lowered and those of the Confederacy soldiers have been boosted, the Union would still have won the war. With the  And since the war was officially about the issue of slavery, the South would not have gained support from Britain and France. If they did, it would look like those foreign countries supported slavery. Which  was a matter that those countries had abolished years ago. If the Confederacy had won the battle, I think that Lincoln would have tried to make peace with the South. Just out of respect for the lives of his soldiers and for the sake of the Union. He could not afford to lose anymore lives in this war, I think he would rather let them be.