 The primary intent of the fort was to protect settlers and travelers in the Mesilla Valley from attacks by desperados and Mescalero Apache Indians.Built near the banks of the Rio Grande, the adobe fort housed units of the California Volunteer Cavalry, U.S. Army Infantry and Cavalry.The first troops to occupy the fort were Company M 1st Regiment of Cavalry, California Volunteers from 31 July 1865 to 31 August 1866, and subsequently companies of the 125th US Colored Infantry Regiment, a group of African-American enlisted soldiers from Kentucky who had been mustered into the Union Army near the close of the American Civil War.