The Battle of Glorieta Pass
The "Gettysburg of the West"
The Battle of Glorieta Pass, fought from March 26 to 28, 1862 in northern New Mexico Territory, was the decisive battle of the New Mexico Campaign during the American Civil War. Dubbed the "Gettysburg of the West" (a term that "serves the novelist better than the historian") by some authors, it was intended as the killer blow by Confederate forces to break the Union possession of the West along the base of the Rocky Mountains. It was fought at Glorieta Pass in the Sangre de Cristo Mountains in what is now New Mexico, and was an important event in the history of the New Mexico Territory in the American Civil War.
There was a skirmish on March 26 between advance forces from each army, with the main battle occurring on March 28. Although the Confederates were able to push the Union force back through the pass, they had to retreat when their supply train was destroyed and most of their horses and mules killed or driven off. Eventually, the Confederates had to withdraw entirely from the territory back into Confederate Arizona and then Texas. Glorieta Pass thus represented the peak of the campaign.
The Confederacy had organized the Confederate Arizona Territory in 1862, a claim that included the southern halves of modern Arizona and New Mexico, after secession moves by residents. The territory had its capital at Mesilla, outside modern Las Cruces. The strategic aim was to capture the gold and silver mines in California and Colorado Territory and the ports in Southern California.
The commanders of the New Mexico Campaign were the Confederate Brigadier General Henry Hopkins Sibley, and the Union Colonel Edward Canby. Sibley, whose mission was to capture Fort Craig, outmaneuvered Canby at the Battle of Valverde in February and drove Canby back to his fort, but failed to force Canby's surrender. Instead, Sibley bypassed the fort, and advanced up along the Rio Grande Valley to seize Santa Fe on March 10. Canby remained at Fort Craig to cut Sibley's logistical support from Texas and to await further reinforcements before resuming the offensive. Sibley set up his headquarters at the abandoned Union storehouse at Albuquerque.
Read more at: https://www.pecosnewmexico.com/attractions/the-battle-of-glorieta-pass
You don't think of civil war battles happening out west but they certainly did occur.
Also, I'm a bit vague on the history but some Southern states did have Union troops. Quite a bit of history and there is a dedicated civil war forum online.
