. >> kevin blackistone is a university of maryland professor and contradictory to the "washington postacing? >> one of the greatest experiments of black relations in this country. >> robinson said he was forced to make a promise that heaved never fight back when players are are fans insulted him. >> when he turned the other check can -- cheek, what was he having to swallow? >> he was having to swallow who he was. he's an educated black man. he knew the pressure on him. he knew he had to perform, he had to be twice as good and he knew he could not respond to all the racism that would be hurled at him as he simply tried to play the game of baseball. >> robinson's mental toughness would be tested repeatedly during his first season says a robinson biographer. he said some of his own teammates didn't want him to succeed. >> you have 399 players in the league, that you have to worry about whether they're going to want you there, throw at your head, spike you on the base paths. death threats from haters. robinson was up against that every day >> belts one high off the screen for a double. >>