Fort Duncan in Texas, also called Camp Eagle Pass was abandoned by Union troops March 20th 1861.
A temporary post was established at a strategic point on the east bank of the Rio Grande River known as Eagle Pass, at the beginning of the Mexican American War in 1846. The permanent post was built there and name Fort Duncan after a Mexican American War hero, Colonel James Duncan. The post was garrisoned on March 27th 1849 by United States Captain Sidney Burbank with three infantry companies. The Fort was important because of its location on the California Road, a significant trade crossing into Mexico. In May 1859 the United States Secretary of War John B Floyd order the Fort abandoned, but United States Lieutenant Colonel Robert E Lee had the Fort reoccupied in March 1860.
With the start of the Civil War the Fort’s Union troops abandoned the post on March 20th 1861. It was occupied within a short time by Confederates using Texas Rangers and volunteers, the name changed to Rio Grande Station. It would serve throughout the war as an important point of trade between the Confederacy and Mexico, with cotton going out and weapons coming in.