Fort Duncan was a United States Army base, set up to protect the first U.S. settlement on the Rio Grande near the current town of Eagle Pass, Texas.

[2] Fort Duncan was established on March 27, 1849, when Captain Sidney Burbank occupied the site with companies A, B, and F of the First United States Infantry.

In 1854, Lt.s Philip Sheridan, Zenas Bliss, Richard W. Johnson and Assistant Surgeon Albert J. Myer were stationed here, the Lieutenants after graduating from West Point.

[4] The CSA garrisoned the fort with volunteers and Texas Rangers, renaming it Rio Grande Station, which became an important port for the export of cotton into Mexico.

[3]: 46 Federal troops reoccupied Fort Duncan on 23 March 1868 by the 41st Infantry under the command of Lt. Col. William R. Shafter, and Lt. Henry Ware Lawton as quartermaster.

[3]: 106  The National Guard was mobilized here in 1916, joining the Coast Artillery Corps,[3]: 94, 109  while the 90th Aero Squadron operated DH-4Bs from here in 1919 until 1920, which included Jimmy Doolittle.

[3]: 116 On 3 March 1911, Benjamin Foulois and Philip Orin Parmelee flew the US military's first cross country reconnaissance flight here from Laredo using a Wright Model B covering 106 miles in two hours at an altitude of 800 feet.