DRIPPING SPRINGS, TEX. - Gen. Antonio López de Santa Anna, the self-described "Napoleon of the West," is ready to inspire some shock and awe among the citizenry of San Antonio. Or, at least, an actor playing him is. Proudly resplendent in gold-braided regalia, the general impassively oversees the advance of his mounted soldiers through the narrow 19th-century streets. Impressed locals spill into a sprawling plaza to noisily cheer the display of military might. Director John Lee Hancock smiles approvingly. He knows this isn't what really happened on that fateful February morning in 1836. But he also knows he has just...