Jefferson Barracks Military Post

The Jefferson Barracks Military Post in Lemay, Missouri, is situated on the Mississippi River, south of St. Louis.  This military post was an important and active U.S. Army installation from 1826 to 1946.  Jefferson Barracks Military Post is the oldest operating U.S. military installation west of the Mississippi River and is currently a base for the Army and Air National Guard.

Site Origin of the Jefferson Barracks Military Post – St. Louis, Missouri

In 1826, General Edmund P. Gaines (Commander of the Western Department of the Army), Brig. General Henry Atkinson (commanding officer of the sixth infantry regiment), explorer William Clark, and Missouri Governor John Miller searched the banks of the Mississippi River for an appropriate location for a new post to replace Fort Bellefontaine.  A site near Carondelet, ten miles south of St. Louis, was recommended and ultimately approved by Major General Jacob J. Brown, Commanding General of the Army.

Two days after the deed to the land was signed on July 10, 1826, six officers and 245 enlisted men, commanded by Brevet Major Stephen Watts Kearny, arrived at the new post and began building temporary quarters.  These quarters were named Cantonment Miller in honor of Governor Miller.

In 1827, the military post was officially named Jefferson Barracks in honor of Thomas Jefferson, who had died the prior year.  Eventually, William Clark’s son, Meriwether Lewis Clark, Sr., joined the ranks of Jefferson Barracks.  It was known as the first “Infantry School of Practice.”

In 1832, the men of Jefferson Barracks fought in their first conflict in the Black Hawk War.  Troops were deployed from Jefferson Barracks to move “hostile Indians” back to what is now Iowa.  Chief Black Hawk was captured and brought to Jefferson Barracks.

In 1832, the United States Regiment of Dragoons, trained to fight mounted or dismounted, were the first unit of permanent cavalry in the United States Army.  They were stationed at Jefferson Barracks. Their name was later shortened to the 1st U.S. Dragoons.

History of Jefferson Barracks Military Military Post

Jefferson Barracks played an important role during the Mexican–American War when it served as a rest and supply station and the recruiting station for most of the U.S. troops deploying to Mexico.

Jefferson Barracks served as a military hospital for both sides and a recruitment depot for the North during the American Civil War.  During the conflict, by the end of the first year, over 5,000 sick and wounded had been admitted to, and well over 18,000 soldiers had been treated at Jefferson Barracks Hospital.
During World War I, Jefferson Barracks served as a training and recruitment station for soldiers heading to Europe.

During the 1930s, the Citizens Military Training Camp was held at Jefferson Barracks.  Young men would spend one month a year at the post being trained as soldiers, and after three years, they could enter the military.

During World War II, Jefferson Barracks was a major reception center for U.S. troops drafted into the military.  It was also an important basic training site for the Army and was later considered the first Army Air Corps Training Site.

At the end of World war II, Jefferson Barracks was decommissioned as a military post.


Jefferson Barracks County Park houses several museums, including museums that feature artifacts and history of Jefferson Barracks while it was an active United States Military Post.