Prairie du Chien was an important location during the war of 1812 because of its location on the Mississippi River. This meant it was key to the fur trade and also controlled access to St Louis, a major US city. During the war, the city changed hands several times.
As a result of the Treaty of Paris 1783 after the American Revolutionary War, both the British and the United States were to have free passage along the Mississippi river. Everything east of the Mississippi from the Lake of the Woods (North of the Headwaters of the Mississippi River) down to where the 31st parallel intercepts the Mississippi River (the current day border between Louisiana and Mississippi) belonged to the USA [3, Article 2]. Despite legally owning the land, the USA did not settle the land. Because there were no settlers, the military did not feel the need to create any outposts in the area. Since the British already had trading posts in Prairie du Chien and the USA wasn’t actually in a position to enforce the treaty, the British kept their trading posts in Prairie du Chien on the United States side of the Mississippi River.
The geographic location of Prairie du Chien made it a desirable place to make a fort. Prairie du Chien had been a thriving part of the fur trade since French Canadians established a trading post. After the British defeated the French in the French and Indian War, the British took over the French territories. This included Prairie du Chien, and as a result the British took over the fur trade.  The British were able to maintain friendly relations with the regions Native American tribes. Not only was Prairie du Chien important economically, it was also the closest settlement to St Louis. If the British were to attack St Louis, it would almost certainly be by sending troops down the Mississippi River. Throughout the spring of 1814 there were multiple conflicts between American settlers and Native American tribes, mostly the Rock River Sac and the Fox tribes. This growing conflict caused the citizens on St Louis to take notice.
Setting the Scene
After the British defeated the French in the Peninsular War on April 17th, 1814 the British could now focus their war efforts on the United States of America. Because of the British’s renewed efforts, the United States felt more at risk of attacks from the British. Understanding the economic and strategic importance, the United States decided they needed a presence in Prairie du Chien in 1814. Missouri Governor William Clark (As in Lewis and Clark), led two hundred troops from St Louis up the Mississippi River with five “gunboats”. [4, p. 7] The boats were effectively keelboats with swiveling guns and cannons mounted on board. On their trip up the Mississippi River, Clark’s forces encountered several groups of Sac or Fox Indians. The Indians were easily scattered or captured and didn’t pose any threat Clark’s mission. The US forces initially arrived on June 2nd, 1814. They are met by very little resistance as the British militia fled after the Indians refused to help defend Prairie du Chien. Clark’s men started building Fort Shelby on June 6th.
After the British militia fled, news made it to the British fort at Mackinaw Island. There was a fur trader named Thomas Anderson who frequently traded in Prairie du Chien who was in Mackinaw at the time. Upon hearing that the Americans had taken Prairie du Chien, he immediately started looking for support to take it back. He went around Mackinaw asking anyone who would listen to join him in reclaiming Prairie du Chien. He quickly was able to round up eighty men, mostly traders who were economically invested. Colonel McDouall noticed the civilian support for taking back Prairie du Chien. He couldn’t send many troops, as Mackinaw had been under a blockade and he feared they would be attacked. None the less, he agreed to arm the volunteers and sent them on their way with three gun-boats. [1, p. 64-65] Along the way Anderson’s volunteer army was able to recruit from several tribes. Roughly two hundred Sioux warriors, one hundred Winnebagoes, seventy-five Menomonees, twenty-five Chippewas, and a dozen Foxes. They also gained another fifty militia men from Green Bay [2, p. 271-272]
The United States had sixty troops, plus officers stationed at Fort Shelby in addition to a gunboat positioned to the west of the fort. On July 17th the force of roughly 650 men led by the British Captain William McKay arrived in Prairie du Chien. The force consisted of British soldiers, local militia, and warriors from the Menominee, Winnebago, and Fox tribes. When they arrived the morning of July 17th, Captain Anderson, the leader of the local militia, approached the fort. “I went immediately with a flag of truce, demanding their surrender. This they refused to do.” Once Captain Anderson returned to his camp both sides opened fire. The British artillery was about to hit Fort Shelby, but it did little damage. The defending US artillery however struggled to hit its mark, “Their six-pound shot, because of their bad powder, did not reach our camp.” [1, p. 66]
At the end of the first day there was little damage on either side, both had two wounded with no casualties. [1, p. 66] The second day of the siege began with the British forces continuing their fire, the United States forces however were running low on ammunition and were unable to return fire. The British bombardier was able to cause enough damage to the US gunboat to force it to retreat south. At this the focus returned to sieging the fort. In an attempt to force the US to surrender Captain McKay began heating iron shot. If the American forces refused to surrender, the fort would be burned to the ground with red hot cannonballs. On the morning on July 20th, lieutenant Perkins surrendered the fort.
The Siege of Prairie du Chien was relatively bloodless with a handful of soldiers wounded and no casualties. After the surrender the Americans were sent down the Mississippi to St Louis. The victorious British remained in control of the fort and renamed it Fort McKay after Captain McKay. The US sent a force to attempt to reclaim Prairie du Chien in late August 1814, but they were repelled by the British forces in the Battle of Credit Island. The British stayed in Prairie du Chien at Fort McKay until May 25th, 1815 when they learned of the Treaty of Ghent which ended the War of 1812. This treaty restored the borders that existed before the war, giving Prairie du Chien back to the Americans. The British burned down Fort McKay as they left so that the Americans would have to start over. 
Reclaiming Prairie du Chien
When the Americans returned to Prairie du Chien in the summer of 1816, they built another fort. They built Fort Crawford in the same location as Fort Shelby/For Mckay. The fort didn’t see much military conflict, but it was an important location for negotiations between the United States and Native American tribes. A garrison of troops stayed at Fort Crawford until 1826 when they were forced out due to a major flood. Seeing an opportunity, chief Red Bird and a group of Winnebago Indians murdered several settlers living near Prairie du Chien. This sparked the Winnebago War in 1827, a short lived series of skirmishes. The Winnebago War forced the United States to return to Prairie du Chien once again. Upon their arrival, they quickly realized the old Fort Crawford had been damaged by the flood. 
So, they built the second Fort Crawford, this time on higher ground a little further inland to protect it from future floods. Construction of the second Fort Crawford took longer than expected. The full construction lasted from 1829 through 1835, but the barracks were completed by 1832.  Once the barracks were completed, the troops were able to abandon the old Fort Crawford. The second Fort Crawford had no conflicts, although after the Battle of Bad Axe Black Hawk surrendered to the United States at Fort Crawford. The United States kept troops stationed at Fort Crawford until 1849 after the Winnebago tribe had been relocated to Minnesota. During the summer of 1855 there were rumors of an Indian uprising, and Fort Crawford once again was filled with troops. Possibly due to the reappearance of troops in Prairie du Chien, there was no revolt and the fort was abandon for good in 1856.
The story of Prairie du Chien is one of policy versus reality. Due to it being a relatively unsettled area during the War of 1812, it mattered much more who was actually there instead of who was supposed to own the land. This theme was repeated several times from when the land was officially awarded to the United States after the Revolutionary War, and when the United States finally was able to enforce their permanent ownership with the completion of the second Fort Crawford.
1. Anderson, Thomas Gummersall. “The British Capture Prairie du Chien during the War of 1812.” From the Draper Manuscripts at the Wisconsin Historical Society, 1870, The British capture of Prairie du Chien
2. Grignon, Augustin. “Seventy-two years’ recollections of Wisconsin.” Wisconsin Historical Collections, 1857, Seventy-two years recollections of Wisconsin
3. “Transcript of Treaty of Paris.” Our Documents – Transcript of Treaty of Paris, 1783, Treaty of Paris
4. Dickey, Michael. The Forgotten War: Missouri from 1812-1815. Friends of Arrow Rock, 2012, The Forgotten War: Missouri from 1812-1815
5. Douglas, Michael. “The Battle of Prairie du Chien: Historical Synopsis.” The War of 1812 in Wisconsin, 2002, The War of 1812 in Wisconsin
6. “Prairie du Chien, Battle of (1814).” Wisconsin Historical Society, 2012, Battle of Prairie du Chien
7. “The First Fort Crawford”, Prairie du Chien Historical Society, The First Fort Crawford
8. “The Second Fort Crawford”, Prairie du Chien Historical Society, The Second Fort Crawford