Spanish Fort (Colorado)
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. The fort was the only Spanish settlement in present-day Colorado. The site of this fort is known today as the Spanish Fort.
Background
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. French and Spanish traders first encountered one another in 1739 along the Arkansas River. The conflicting claims of France and Spain to the upper Arkansas River basin were resolved in 1762 when Louis XV of France transferred the French colony of La Louisiane to Charles III of Spain with the secret Treaty of Fontainebleau.The conflict between France and Spain was reignited in 1800 when Napoléon Bonaparte demanded that Charles IV of Spain return the Spanish colony of Luisiana to the French Republic with the secret Third Treaty of San Ildefonso. Napoléon then sold La Louisiane to the United States with the Louisiana Purchase Treaty of 1803. The United States maintained the claim of France to the entire Mississippi basin, while Spain asserted its claim to the southwestern portion of the basin.
In 1806, a U.S. Army reconnaissance expedition led by Captain Zebulon Pike explored the upper Arkansas River. In January 1807, the expedition left the upper Arkansas Valley and crossed the treacherous snow-covered Sangre de Cristo Range into the San Luis Valley, the undisputed territory of Santa Fe de Nuevo México. On February 26, 1807, Pike and his expedition were arrested by Spanish cavalrymen from Santa Fe.