quality:corruption
American West, 1813–1815

The Mississippi River valley was the western frontier of the United States in 1812. The territory acquired in the Louisiana Purchase of 1803 contained almost no American settlements west of the Mississippi except around St. Louis and a few forts and trading posts in the Boonslick. Fort Belle Fontaine was an old trading post converted to an Army post in 1804 and this served as regional headquarters. Fort Osage, built in 1808 along the Missouri River, was the westernmost American outpost, but it was abandoned at the start of the war. Fort Madison was built along the Mississippi in Iowa in 1808 and had been repeatedly attacked by British-allied Sauk since its construction. The United States Army abandoned Fort Madison in September 1813 after the indigenous fighters attacked it and besieged it – with support from the British. This was one of the few battles fought west of the Mississippi. Black Hawk played a leadership role.

The American victory on Lake Erie and the recapture of Detroit isolated the British on Lake Huron. In the winter a Canadian party under Lieutenant Colonel Robert McDouall established a new supply line from York to Nottawasaga Bay on Georgian Bay. He arrived at Fort Mackinac on 18 May with supplies and more than 400 militia and Indians, then sent an expedition which successfully besieged and recaptured the key trading post of Prairie du Chien, on the Upper Mississippi. The Americans dispatched a substantial expedition to relieve the fort, but Sauk, Fox, and Kickapoo warriors under Black Hawk ambushed it and forced it to withdraw with heavy losses in the Battle of Rock Island Rapids. In September 1814, the Sauk, Fox, and Kickapoo, supported by part of Prairie du Chien's British garrison, repulsed a second American force led by Major Zachary Taylor in the Battle of Credit Island. These victories enabled the Sauk, Fox, and Kickapoo to harass American garrisons further to the south, which led the Americans to abandon Fort Johnson, in central Illinois Territory. Consequently, the Americans lost control of almost all of Illinois Territory, although they held onto the St. Louis area and eastern Missouri. However, the Sauk raided even into these territories, clashing with American forces at the Battle of Cote Sans Dessein in April 1815 at the mouth of the Osage River in the Missouri Territory and the Battle of the Sink Hole in May 1815 near Fort Cap au Gris. This left the British and their Indian allies in control of most of modern Illinois and all of modern Wisconsin.

Meanwhile, the British were supplying the Indians in the Old Northwest from Montreal via Mackinac. On 3 July, the Americans sent a force of five vessels from Detroit to recapture Mackinac. A mixed force of regulars and volunteers from the militia landed on the island on 4 August. They did not attempt to achieve surprise, and Indians ambushed them in the brief Battle of Mackinac Island and forced them to re-embark. The Americans discovered the new base at Nottawasaga Bay and on 13 August they destroyed its fortifications and the schooner Nancy that they found there. They then returned to Detroit, leaving two gunboats to blockade Mackinac. On 4 September, the British surprised, boarded, and captured both gunboats. These engagements on Lake Huron left Mackinac under British control.

The British returned Mackinac and other captured territory to the United States after the war. Some British officers and Canadians objected to handing back Prairie du Chien and especially Mackinac under the terms of the Treaty of Ghent. However, the Americans retained the captured post at Fort Malden near Amherstburg until the British complied with the treaty. Fighting between Americans, the Sauk and other indigenous tribes continued through 1817, well after the war ended in the east.