Defender of the Southwest
When New Mexico became United States territory after the U.S.- Mexican War, the army established garrisons in towns scattered along the Rio Grande to protect the area's inhabitants and travel routes. This arrangement proved unsatisfactory for a number of reasons, and in April 1851, Lt. Col. Edwin V. Sumner, commanding Military Department No. 9 (which included New Mexico Territory), was ordered "to revise the whole system of defense" for the entire territory. Among his first acts was to break up the scattered garrisons and relocate them in posts closer to the Indians. He also moved his headquarters and supply depot from Santa Fe, "that sink of vice and extravagance," to a site near the Mountain and Cimarron branches of the Santa Fe Trail, where he established Fort Union.