Fort Union

From Justinfo Wiki, the open reference

Fort Union was a United States Army post on the Santa Fe Trail in northeastern New Mexico Territory, established in 1851 and serving as the principal supply depot for the military district.

Its stores made it the objective of the Confederate advance in 1862, and the 1st Colorado Volunteer Infantry marched from Denver to reinforce it in March of that year. The post was abandoned in 1891 and its adobe ruins are now a national monument.