The US military even acknowledges the battle as one of its if not the worst defeat in US military history.
War of 1812, Blandesburg... That is the worst defeat in American history. It was a a few thousand militia, a few thousand regulars up against battle-hardened British. Within 20 minutes, the American center collapsed, followed by the left 20 minutes later, and then the right just after. The British forced the Americans to retreat so fast, the Americans all ran back to Washington D.C. and the British sacked the capital 5 days later.
That's the worst loss in American history. That, and 'Nam.