Fort Armstrong , Illinois Fort Armstrong ( 1816 – 1836 ) , was one of a chain of western frontier defenses which the United States erected after the War of 1812 . It was located at the foot of Rock Island , Illinois , in the Mississippi River between present - day Illinois and Iowa . It was five miles from the principal Sac and Fox village on Rock River in Illinois . Of stone and timber construction , 300 feet square , the fort was begun in May 1816 and completed the following year . In 1832 the US Army used it as military headquarters during the Black Hawk War . It was garrisoned until 1836 , usually by two companies of United States regulars . Island before the fort . In 1805 , when President Thomas Jefferson sent Lewis and Clark on their expedition into the Louisiana Territory , he also sent Lieutenant Zebulon Pike and Major Stephan H . Long up the Mississippi River to gather data and determine strategic sites for forts . Pike identified one site as the " big island ; " Congress agreed with his recommendation , reserving the island for military use in 1809 and naming it Rock Island . The Sauk considered the island sacred : This [ island ] was the best one on the Mississippi , and had long been the resort of our young people during the summer . It was our garden , like the white people have near their big villages , which supplied us with strawberries , blackberries , gooseberries , plums , apples and nuts of different kinds . Being situated at the foot of the rapids , its waters supplied us with the finest fish . In my early life I spent many happy days on this island . A good spirit had charge of it , which lived in a cave in the rocks immediately under the place where the fort now stands . This guardian spirit has often been seen by our people . It was white , with large wings like a swan ' s , but ten times larger . We were particular not to make much noise in that part of the island which it inhabited , for fear of disturbing it . But the noise at the fort has since driven it away , and no doubt a bad spirit has taken its place . Construction . This was to be the second US fort between St . Louis and Prairie du Chien , Wisconsin . The US wanted to establish a military presence to dissuade the French and English Canadians ( who traded in areas nearby ) from encroaching upon the unorganized territory . After its losses at several forts during the War of 1812 , the US Army wanted to increase its presence on the Mississippi frontier . The fort also would serve to protect American settlers within the area and to help control or remove the Sauk , the American Indians in the region . The Sauk disapproved of its construction ; Black Hawk wrote in his memoir , " When we arrived we found that the troops had come to build a fort on Rock Island . This , in our opinion , was a contradiction to what we had done – ' to prepare for war in time of peace . ' We did not object , however , to their building their fort on the island , but were very sorry . " On May 10 , 1816 , soldiers arrived to begin construction of Fort Armstrong . It was named after John Armstrong , the Secretary of War under President James Madison . 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 . Cholera outbreak . During the Black Hawk War ( 1832 ) , General Winfield Scott led 1000 troops to Fort Armstrong to assist the garrison and volunteers stationed there . While they were en route along the Great Lakes , General Scott ' s troops contracted cholera ; it killed most of the 1000 men . Only 220 of the original force made the final march from Chicago to Rock Island . Scott and his troops likely carried the disease with them ; soon after their arrival at Rock Island , a cholera epidemic broke out among whites and Indians in the area of the fort . It would have been spread through the water by the poor sanitation practices of the day . Within eight days , 189 persons died and were buried on the island . Black Hawk Treaty . On September 21 , 1832 , the Black Hawk War officially came to an end with the treaty signed at Fort Armstrong . The defeated Sauk and Fox Indians agreed to cede to the US the lands they occupied east of the Mississippi River . Black Hawk , two of his sons , and other Sac and Fox warriors had been taken to the fort as prisoners after their captures following the Massacre at Bad Axe . They spent the winter held at Jefferson Barracks in St . Louis , after which the Army took the men on a tour of Eastern cities , hoping to impress them with the wealth and power of white civilization . The natives met with President Andrew Jackson and were of great interest and celebrity among the white population , who at that period admiringly viewed natives as " noble savages . " After a brief period of imprisonment at Fortress Monroe at Hampton Roads , Virginia , the Sauk and Fox warriors were allowed to return to Iowa . Together with their people , they occupied a small reservation in Iowa allotted by the Treaty of Fort Armstrong . Black Hawk died there in 1838 .