History: American Old West, United States

Civil War in the West
At the outset of the American Civil War, Westerners looked to the Civil War to settle the question of slavery in their territories. But they also feared that the federal government would be too preoccupied with the war to worry about the stability of the territorial governments and that lawlessness might spread. The Dred Scott Decision had made the choice of making slavery legal in all of the land west of the Mississippi River, except for Kansas, Oregon, and California.
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.