When President Thomas Jefferson sent Lewis and Clark on their expedition to explore the western portion of North America, he also sent Lieutenant Zebulon Pike up the Mississippi River to collect data and select sites for strategic military forts along the Mississippi River. He chose this site, Fort Armstrong as one of those strategic strongholds.
The US wanted to establish a military presence to dissuade the French and English Canadians (who traded in areas nearby) from encroaching upon the yet to be organized territory. Fort Armstrong also would serve to protect American settlers within the area and to help control or remove the Sauk natives.
Fort Armstrong was the second US fort between St. Louis and Prairie Du Chien, Wisconsin.
The fort was named after John Armstrong, the Secretary of War under President James Madison. Its construction began on May 10, 1816. The army assigned 600 soldiers and 150 laborers to the project. After the construction was completed, fewer than 200 soldiers garrisoned the post. Between 1824 and 1836, the garrison was reduced to fewer than 100 troops.
During the Black Hawk War of 1832, General Winfield Scott led 1000 troops, to Fort Armstrong, to assist the US Army Garrison and militia volunteers stationed there. While General Scott's army was en route, along the Great Lakes, his troops had contracted cholera, killing most of his 1,000 soldiers, before they left New York state. Only 220 U.S. Army regulars, from the original force, made the final march to Fort Armstrong. Winfield Scott and his troops likely carried the cholera with them, and soon after their arrival, a local cholera epidemic broke out around the area of Fort Armstrong. Within eight days of their arrival, 189 people died and were buried on the island.
On September 21, 1832, the Black Hawk War officially came to an end with the treaty signed at Fort Armstrong. The fort officially closed in 1836.
Between 1833 and1840, other buildings were being used at the Fort Armstrong site: a blacksmith building, a building for the Indian agent and other buildings were used by the Indian Bureau. The Indian agency was removed in 1840.
In 1840, an Army Depot was established at the Fort Armstrong site. Small Arms were shipped to the western points until 1845. In 1840, Colonel Talcott, the Chief of Ordnance gave orders to Captain William H. Bell, the commanding officer of the St. Louis Arsenal to examine and report on the island of Rock Island to see if a supply depot could be put there. Later in 1840, Captain W. R. Shoemaker, who was an Ordnance Store Keeper took command of Fort Armstrong. 5,000 muskets, 5,000 sets of accouterments, 6 sets of artillery harnesses and equipment and 6 pieces of field cannon were supplied to the Fort. Official records do not mention if there was a detachment of Ordnance enlisted men serving there. The supply depot remained active until the Mexican War began in 1844. All ordnance supplies were ordered to be shipped to the St. Louis Arsenal.
Fort Armstrong was never used for any military purpose again and in 1855 and 1859, what remained standing was destroyed by fire.