History: American Old West, United States

Although most of the battles of the Civil War took place east of the Mississippi River, a few important campaigns occurred in the West. However, Kansas, a major area of conflict building up to the war, was the scene of only one battle, at Mine Creek. But its proximity to Confederate states enabled guerillas, such as Quantrill's Raiders, to attack Union strongholds, causing considerable damage. Both sides attacked civilians, murdering and plundering with little discrimination, creating an atmosphere of terror.
In Texas, citizens voted to join the confederacy. Local troops took over the federal arsenal in San Antonio, with plans to grab the territories of northern New Mexico, Utah, and Colorado, and possibly California. Confederate Arizona was created by Arizona citizens who wanted protection against the Apache after the United States Army abandoned them to go fight in the South. At the Battle of Glorieta Pass, the Confederate campaign was defeated strategically by Union troops from Colorado and from Fort Union. Missouri, a Union state where slavery was legal, became a battleground when the pro-secession governor, against the vote of the legislature, led troops to the federal arsenal at St. Louis. When Confederate forces from Arkansas and Louisiana joined him, Union General Samuel Curtis was dispatched to the area and regained Missouri for the Union for the duration of the war.
The decreased presence of Union troops in the West left behind untrained militias which encouraged native uprisings and skirmishes with settlers. President Lincoln appears to have had little time to formulate new Indian policy. Some tribes took sides in the war, even forming regiments that joined the Union or the rebel cause, while others took the opportunity to avenge past wrongs by the federal government. Engagements were fought against natives in Utah against the Shoshone, all across New Mexico Territory against Apaches and the Navajo, conflict also occurred in Oregon. Within the Indian Territory, now Oklahoma, conflicts arose among the Five Civilized Tribes, some of whom sided with the South being slaveholders themselves.
While the question of whether western territories would be free or slave-owning had preoccupied antebellum political debate, in 1862, Congress enacted two major laws to facilitate settlement of the West: the Homestead Act and the Pacific Railroad Act.