The New Mexico Campaign was a military operation of the American Civil War from February to April 1862 in which Confederate Brigadier General Henry Hopkins Sibley invaded the northern New Mexico Territory in an attempt to gain control of the Southwest, including the gold fields of Colorado and the ports of California. Historians regard this campaign as the most ambitious Confederate attempt to establish control of the American West and to open an additional theater in the war. It was an important campaign in the war's Trans-Mississippi Theater, and one of the major events in the history of the New Mexico Territory in the American Civil War.
The New Mexico Campaign ended in failure for the CSA during the War of Secession in 1862. Because of this, the US Forces in New Mexico Territory were too strong, and the CSA was unable to get the territory partitioned like Virginia and West Virginia. So the territory stayed with the United States in the ensuing peace. In the years following the war, many in the Confederate States regarded this failure as a burr in their side, because it didn't allow the country to stretch all the way to the Pacific.
In 1881, when General Stuart took command of the Mexican provinces of Chihuahua and Sonora, he also planned for protecting his supply lines, as he remembered bitterly General Sibley's main reason for failure in the New Mexico Campaign was a lack of supplies which forced him to withdraw.