Battles of the American Civil War were fought between April 12, 1861 and May 12–13, 1865 in 24 states (Alabama, Arkansas, Florida, Georgia, Kansas, Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Vermont, Virginia, and West Virginia), the District of Columbia, as well as the following territories: Arizona Territory, Colorado Territory, Dakota Territory, Indian Territory (present-day Oklahoma), New Mexico Territory, and Washington Territory, and naval engagements. These battles would change the standing and historical memory of the United States. While the origins of the war are complex, principal among them were the issue of slavery, and the interpretations of the Constitution and the rules, rights, and qualifications that it embodied.