Well what is now Missouri anyway - at the time it was Missouri Territory. The battle of New Orleans a few months earlier was the last battle fought with regular army soldiers, but the Missouri Rangers were a duly authorized force. So the war formally ended on December 24, 1814 with the signing of the Treaty of Ghent in Belgium, the Battle of New Orleans occured on January 1815 and the Battle of the Sinkhole happen in May 1815. News travelled slowly back then.