Fifty years ago, when Hitler's tanks were poised at the English Channel and his bombers were pounding London, Franklin D. Roosevelt decided that the U.S., though still neutral, had to supply Britain with the military equipment it desperately needed. "We must admit that there is risk in any course we may take," F.D.R. said on a national radio broadcast. But backing America's natural ally "involves the least risk now and the greatest hope for world peace in the future."
America's resolution came very late -- almost too late -- in the game. Now the slow reactions that helped produce World War...