Fort Lyon

Fort Lyon, first named Fort Wiz, was operated on the Colorado eastern plains until 1867. That year a new fort called Fort Lyon, and later Las Animas, Colorado, U.S. Naval Hospital and 5BN117, was built near the present-day town of Las Animas, Colorado. First named after Virginia governor Henry Wise, the fort was renamed in 1862 during the American Civil War. The US Army named it after General Nathaniel Lyon, who was killed in the Battle of Wilson's Creek near Springfield, Missouri in 1861.

Old Fort Lyon was notable as the staging post used by Colonel John Chivington in 1864 as he led an attack by the Third Colorado Cavalry and other forces on friendly Cheyenne and Arapaho camps that became known as the Sand Creek Massacre. As witnesses and survivors emerged, the US Congress investigated, with a resulting national wave of public outrage about the slaughter and mutilation of up to 163 people, primarily women, children, and the elderly. The campground has been designated a National Historic Site.

In 1866 after flooding on the Arkansas River, the US Army established a new fort near Las Animas. The facility was completed in 1867. Angry Indians burned the old fort after the Army left. The U.S. Army used Fort Lyon until 1897, when they abandoned it after the end of the Indian Wars.

In 1906, the U.S. Navy opened a sanitorium there to treat sailors and marines with tuberculosis. The dry climate and rest by isolation at the fort were thought to be beneficial by contemporary treatment methods. On June 22, 1922, the Veteran's Bureau assumed operations. In 1930, administration of the hospital was transferred to the newly created Veterans Administration. Within three years, the VA designated Fort Lyon a neuropsychiatry facility.

In 2001 the hospital was closed and the facility was turned over to the state of Colorado for conversion to a minimum security prison. The Fort Lyon National Cemetery, which began burials in 1907, remains open. The fort is listed on the National Register of Historic Places.