In 1862, the Territorial Militia, also known as the New Mexico Volunteers, played a decisive role in the defeat of Confederate forces in the Battle of Glorieta Pass.

Many New Mexico Guardsmen helped form the 2nd Squadron, 1st United States Cavalry, which served with Roosevelt at the legendary charge of San Juan Hill.

After World War I, the Guard in New Mexico began to be reorganized under the National Defense Act of 1920, eventually forming the 111th Cavalry Regiment, the 120th Engineers (less the Medical Detachment and 1st Battalion), and Battery A, 158th Field Artillery.

In 1939, the War Department suggested the 111th Cavalry convert to another branch of service, and the officers of the command jointly selected Coast Artillery.

At about 0300 hours on 8 December 1941, the 200th went on full alert when the night radio crew picked up commercial broadcasts telling of the Japanese attack at Pearl Harbor, Hawaii.

During the 1983–1989 time frame the New Mexico Army National Guard began a complete modernization program to gain high technology type units.