The Arizona Territory, colloquially referred to as Confederate Arizona, was an organized incorporated territory of the Confederate States of America that existed from August 1, 1861, to May 26, 1865, when the Confederate States Army Trans-Mississippi Department, commanded by General Edmund Kirby Smith, surrendered at Shreveport, Louisiana. However, after the Battle of Glorieta Pass, the Confederates had to retreat from the territory, and by July 1862, effective Confederate control of the territory had ended.Delegates to the secession convention had voted in March 1861 to secede from the New Mexico Territory and the Union, and seek to join the Confederacy. It consisted of the portion of the New Mexico Territory south of the 34th parallel, including parts of the modern states of New Mexico and Arizona. The capital was Mesilla, along the southern border. The breakaway region overlapped Arizona Territory, established by the Union government in February 1863.
Arizona was proclaimed a Confederate territory on August 1, 1861, after Colonel John R. Baylor's victory at the Battle of Mesilla. His hold on the area was broken after Glorieta Pass (March 26–28, 1862), the defining battle of the New Mexico Campaign. In July 1862, the Confederate territorial government withdrew to El Paso, Texas. With the approach of Union troops, it relocated to San Antonio, where it remained for the duration of the civil war. The territory continued to be represented in the Confederate States Congress, and Confederate troops continued to fight under the Arizona banner until the war ended.