William Clark Governor of the Missouri Territory was in command of a large force of regulars and militia. In May 1814 they marched quickly up the Mississippi River and brushed aside the Sac warriors who attempted to stop them at Rock Island rapids.
The post at Prairie du Chien was held by a small British artillery detachment commanded by Captain Francis Michael Dease. Captain Dease ordered his troops to withdraw after learning that a large American force was on it's way.
When the Americans did arrive at the post they found it deserted. William Clark made plans for a small fort and then returned to St. Louis, leaving Lieutenant Joseph Perkins and approximately 65 men of the 24th U.S. Infantry to finish the construction of the defences. In addition to the 24th Infantry, Clark also ordered the "Governor Clark" river gunboat with a crew of 80 men to help defend the fort. The fort not yet completely finished was named for Governor Isaac Shelby of Kentucky. The 24th Infantry pulled out and a garrison of seventy soldiers from the 7th U.S. Infantry were left under the command of Lieutenant Perkins. The fort had two blockhouses and was armed with several cannons.
British Colonel Robert McDouall at Fort Mackinac ordered an expedition to dislodge the Americans from Prairie du Chien. McDouall assigned Captain William McKay of the Michigan Fencibles, who he promoted to acting lieutenant-colonel. He also sent Sergeant James Keating with a three-pounder gun.
Leaving Fort Mackinac on June 28th this force gathered reinforcements, they arrived at Prairie du Chien on July 17th with approximately 650 men, mostly Indians.
The arrival of the British force took the American commander by surprise, work was still being done on Fort Shelby' defences. The British however, did not attack immediately, instead they ordered Lieutenant Perkins to surrender unconditionally. Perkins refused to surrender Fort Shelby, and the British laid siege to the fort. Sergeant Keating's 3 pounder had little effect on the American fort, but it did land several hits on the gunboat "Governor Clark" which was anchored in the river. After taking repeated hits from the British artillery the "Governor Clark" slipped it's cable and retreated down river.
Without support from the gunboat the Americans held out for two more days. With most of their ammunition expended and the forts only well dry, and the British ready to attempt an assault the Americans had no chioce but to surrender the fort and their arms. The American garrison was allowed free passage to St. Louis by boat as a condition to this surrender. Credit must also be given to the British commander for keeping the Indians under control while the Americans made their way out of the fort.
The British renamed the post "Fort McKay" to impress the local indians and held the fort for the remainder of the war. After the Treaty of Ghent they abandoned the fort on May 25th 1815, and burned it on their departure. There was one more attempt to take the fort by the Americans, this was known as the Battle of Rock Island Rapids