By the end of the Super Bowl on Sunday night, one or more professional football players will be hailed for their valor, for their guts, for their devotion to their teammates. They will be called heroes. And more than 100 million people will be watching. But because, predictably, those laudatory words will be thrown around so casually on Sunday, perhaps we can take a few minutes here to address an act of genuine valor that happened exactly 70 years ago today. It wasn’t televised. There were no sponsors. On February 3, 1943, an Army transport ship called the Dorchester, carrying American soldiers through the icy North Atlantic on their way to serve in World War II, was about 100 miles off the coast of Greenland in rough sea. More than 900 people were on board….