Wabash

You've heard of US military tragedies like Pearl Harbor and Custer's Last Stand, but arguably the worst defeat on a US army force is so unknown that it doesn't even have a name. Most call it St. Clair's defeat, named after the general who lost 1/3 of the US's standing army in a single morning. We call it Battle of the Wabash, named after the river where a smaller Native American force wiped out an American encampment on November 4, 1971.