New Mexico Territory in the American Civil War

The New Mexico Territory, comprising what are today the U.S. states of New Mexico and Arizona, as well as the southern portion of Nevada, played a small but significant role in the trans-Mississippi theater of the American Civil War. Despite its remoteness from the major battlefields of the east, and its being part of the sparsely populated and largely undeveloped American frontier, both Confederate and Union governments claimed ownership over the territory, and several important battles and military operations took place in the region.

Source: Wikipedia — New Mexico Territory in the American Civil War (CC BY-SA 4.0)