Why were the reasons for Battle of Gettysburg?

Question:

US Civil War

In April 1861, the United States was engaged in a bloody civil war over the question of slavery and pitted the Northern States, or Union, who were predominantly against the institution of slavery, versus the Southern States, or Confederacy, who were mainly for the continuation of slavery. The war would last four years and result in hundreds of thousands of deaths. In the end, the Union was victorious and this led to the passage of constitutional amendments which outlawed slavery and eventually allowed African American men the right to vote.

Answer and Explanation: