After the 1783 Treaty of Paris ended the American Revolution there were many disputes between the United States and Great Britain concerning the boundary lines of the Great Lakes. Originally the Upper Peninsula was of no use to the Americans so there weren't many concerns over its boundaries until the War of 1812 when hostilities resumed between the British and the Americans. Disputes began over the border within the Saint Mary's River, which covered sixty miles of waterway. War broke out amongst the fleets and armies stationed along the common borders.

On December 24, 1814, President John Madison's administration reached a formal agreement for peaceful determination of the boundary. This ended the War of 1812. In the formal agreement, two commissioners, one from the United States and one from Great Britain, would determine the boundaries after surveying and mapping the land. The commissioners began their work in May of 1817.

In the summer of 1815 the British surrendered Fort Mackinac to the US and its garrison withdrew to Drummond Island to command the outlet of the Saint Mary's River. From this vantage point the British government sought to maintain its ancient contact with the tribes around the upper lakes and to control the fur trade. The main concern was the Chippewa Indians of Sault Ste. Marie. This tribe was dependent on the traders coming from the west and east, trading food, tools, and weapons for furs and some medicines. They saw no reason to welcome American rule under the new formal agreement of 1814. The Chippewas instead chose to continue their allegiance to Great Britian. Once they had undisputed control of the region the American government moved to establish effective control over the northwestern tribes and region. The American government decided to establish a garrison along all lake side shores and end British dominance in trading. This would give countenance to the operations of American fur traders. New garrisons were established and built at Green Bay, Rock Island, Praire du Chein, and Fort Snelling and Sault Ste. Marie. In order to build in the Sault the government had to first receive consent from the Chippewas, since all their land had been returned to them with the treaty with Indian tribes in 1815. The government sent Governor Lewis Cass of the Michigan territory to conduct negotiations.

Cass arrived in Sault Ste. Marie in the summer of 1820 and held a council meeting with the Chippewas at which he explained the intention of the government to establish a fort. After the explanation many members of the tribes were angered. Sassaba, brother of Chief Shingabowassin, retrieved a British flag from his village, marched up the hill and planted it there in defiance of Cass. Cass took down this flag and threw it to the ground, declaring that the American government could and would destroy their village. Chief Shingabowassin was summoned by Susan Johnston and he then calmed his brother down. It was the great chief who stopped blood shed from happening that day. At a later council meeting sixteen square miles were ceded to the American government for the Sault garrison.

In the summer of 1822 a battalion of the Second United States Regiment arrived from Sackett's Harbor under the command of then-Colonel Hugh Brady. The Fort was then constructed under Colonel Brady's direction.

First Fort