The Texas-Santa Fe Expedition was the idea of Texas President Mirabeau Lamar, who served from 1838 through 1841. It was intended to establish Texan control of what is now eastern New Mexico, which would lead to Texan control of a strip of land that ran north through Colorado and southern Wyoming. The plan was to establish the Republic of Texas as a major power on the continent.
It included 21 ox carts of merchandise worth some $200,000 and included some three hundred soldiers. It was largely crippled due to poor planning, a lack of fresh water, and Indian raids. After their Mexican guide fled, a detachment was sent to find Santa Fe. Rather that finding a population eager to trade and to join the Republic, they encountered the Mexican army and were taken prisoner. The rest of the group and were also taken prisoner. While promised fair treatment, the commander of Mexican reinforcements countermanded this. There was a vote about whether to massacre the "Texians", whose lives were spared by one vote. They were taken to Mexico City then released, eventually arriving in New Orleans. Of the original group of approximately 400 men, only 47 survived.
Rather than strengthening President Lamar's claim, it showed that the Texians could not defend their claimed territories. With Lamar leaving Texas in serious debt, Sam Houston was elected; leading the Republic to its successful petition to join the Union in 1844. The New Mexico section was not included, due to the political climate requiring the maintaining of the balance of slave states and free states.