The American Civil War took place primarily in the United States, specifically within the territories controlled by the Union (the Northern states) and the Confederacy (the Southern states). The war was mostly concentrated in the eastern parts of the country, with major battlefields located in states such as Virginia, Maryland, Pennsylvania, and Tennessee. Additionally, military operations occurred in various western states and territories, extending as far west as New Mexico and Arizona. Naval skirmishes and blockades also took place along the Atlantic and Gulf coasts, as well as on major rivers such as the Mississippi and Tennessee. Overall, the Civil War was a nationwide conflict that engulfed much of the continental United States.