This Day in Baseball History: July 4, 1939 > The New York Yankees retire Lou Gehrig's No. 4 in an emotional ceremony at Yankee Stadium. In one of the most famous moments in baseball history, the "Iron Horse" tells 62,000 fans that he considers himself "the luckiest man on the face of the earth." Less than two years later, Gehrig will succumb to the life-threatening disease that bears his name.