Actually, George Washington inadvertantly started the French & Indian War when he and his men opened fire on a group of Indians. Only Congress can DECLARE war, but the Commander in Chief can dispatch them and the War Powers Act during Vietnam gave the president vastly expanded powers. We haven't been in a declared war since WWII... If you notice they're usually called "police actions" or "operation this, or that" Vietnam wasn't a "war" although it's called one... Officially it was an action.