General Order Number 20

During the Mexican War, General Winfield Scott, who was commanding the American invasion that would take Mexico City and win the War, was concerned about crimes committed by American troops, especially volunteers, against the Mexican civilian population.  (The crimes were often precipitated by the anger of American troops at sickening mutilation and murder of Americans captured by Mexican guerillas.)  Up to this time, American soldiers accused of crimes against civilians had simply been tried in American civilian courts.  This was clearly not an option available during a war waged on foreign soil.  Scott hit upon the idea of trying troops before military commissions, and he embodied this idea in Order Number 20.  Here is the text of the order: