History & Culture


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.

Explore the First Fort Union

Explore the Second Fort Union

Explore the Third Fort Union


If you want to read a more in-depth study of the Fort's history, Leo E. Oliva in 1993 wrote The Tome, which is the defining published work on the history of Fort Union. He worked out of the Division of History for the National Park Service in Santa Fe, New Mexico.

Fort Union and the Frontier Army of the Southwest: A Historic Resource Study Fort Union National Monument Fort Union, New Mexico (7.03 mb)

Last updated: November 9, 2017

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