Fort Union

Fort Union was the biggest fort in the Southwest — three successive posts on the Mora prairie where the Santa Fe Trail's two branches split, the first one Sumner threw up in 1851, the second a Civil War earthwork, the third the adobe city that took five years to build and became the largest military installation west of the Mississippi. The 120-foot flagstaff was the first sign of American civilization after 500 miles of prairie from Council Grove — welcome to the traders, ominous to the Jicarilla Apache whose hunting ground it stood on.

The fort earned its size by feeding everything — it was the quartermaster depot for the entire Southwest, the arsenal that supplied the other posts, and in 1862 the garrison that marched to Glorieta Pass and broke the Confederate invasion of New Mexico. The third fort's adobe walls went up on stone foundations, plastered and trimmed with brick hauled up the Trail it guarded — and the roofs leaked from the day they were finished, the adobe needing constant patching against the weather the troops were supposed to be protected from.

The railroad killed it — the AT&SF reached New Mexico in 1879, the Trail it guarded stopped being a trail, and on February 21, 1891 the Tenth Infantry marched out singing 'There's a Land that is Fairer than This' while the largest post in the West was left to the weather. The ruins are the monument now — the adobe walls melting back into the prairie, the best-preserved Santa Fe Trail ruts still cut in the grass, and the foundations of three forts where the biggest one in the Southwest stood.

Fort Union is the archive's grand file — the three-fort complex that was the Southwest's military capital, the Glorieta garrison, and the adobe ruins of the largest post west of the Mississippi where the Trail ruts are still in the grass.