Fifty years ago on Saturday, an innocuous fourth inning at Dodger Stadium gave way to an indelible moment in baseball -- and American -- history. On April 25, 1976, the Dodgers hosted the Cubs in the rubber match of a three-game series. In the bottom of the fourth inning, two fans jumped the left-center field fence and hurried onto the outfield grass. Chicago center fielder Rick Monday noted a sound that didn’t match the rhythm of the game. He glanced to his right and saw the trespassers huddled over, unfurling an American flag. “I can see the guy pull out...