The US was slow to present any authority over Prairie du Chien, but late in the War of 1812 when the government realized the importance of holding the site to prevent British attacks from Canada, it began construction of Fort Shelby in 1814. In July, British soldiers captured the fort during the Siege of Prairie du Chien. The British maintained control over the city until the war's end in 1815. Not wanting another invasion through Prairie du Chien, the Americans constructed Fort Crawford in 1816.