In 1942, with the U.S. military still gearing for battle, Hitler brought the war to America. In a little known mission, dozens of Nazi U-boats penetrated the Gulf of Mexico, attacking and sinking numerous merchant freighters and oil tankers. While experts thought they knew most of what went on there, their theories were challenged in 2001 when an underwater survey team discovered the wreck of U-166 on the Gulf’s seafloor–over 140 miles distant from where records said she sank.