The Arizona Organic Act was a United States federal law introduced as H.R. 357 in the 2d session of the 37th Congress on March 12, 1862, by Rep. James M. Ashley of Ohio. The Act provided for the creation of the Arizona Territory by the division of the New Mexico Territory into two territories, along the current boundary between New Mexico and Arizona. The bill was driven by the desire to ensure that Arizona would not be a pro-slavery territory, as was New Mexico. The provisional government established by the bill abolished slavery in the new Arizona Territory, but did not abolish it in the portion that remained the New Mexico Territory. On February 24, 1863, President Abraham Lincoln signed the bill once it had been approved by Congress.
Nevertheless, for a brief time during the Civil War, Arizona became part of the Confederacy, and invading Confederate troops brought an unknown number of enslaved African Americans into the territory. The Confederate loss at the Battle of Glorieta Pass forced Confederate retreat from the territory. (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” by some historians, 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.)
The following month a small Confederate picket troop north of Tucson fought with an equally small Union cavalry patrol from California in the so-called Battle of Picacho Pass. A Union cavalry patrol of 13 men from California skirmished with 10 Confederate scouts from Texas. Eleven men in all were killed. This marks the westernmost battle of the American Civil War. (Every March, Picacho Peak State Park hosts a re-enactment of the Civil War battles of Arizona and New Mexico, including the battle of Picacho Pass. The re-enactments now have grown so large that many more participants tend to be involved than took part in the actual engagements, and include infantry units and artillery as well as cavalry.)