A Spanish military fort was constructed and occupied in 1819 near Sangre de Cristo Pass in the present U.S. State of Colorado to protect the Spanish colony of Santa Fe de Nuevo México from a possible invasion from the United States.

When René-Robert Cavelier, Sieur de La Salle claimed the Mississippi River and its entire drainage basin for Louis XIV of France in 1682, he was unaware that the southwestern reaches of the basin extended into territory claimed by Charles II of Spain for the New Spain colony of Santa Fe de Nuevo Méjico.

In 1806, a U.S. Army reconnaissance expedition led by Captain Zebulon Pike explored the upper Arkansas River.

The fort was occupied by a detachment of approximately one hundred soldiers who patrolled the area in search of Ute Indians and foreigners.

On August 24, 1821, Ferdinand VII of Spain finally recognized the independence of Mexico with the signing of the Treaty of Córdoba.