This case traces the life of Robert McNamara from Harvard Business School to Ford Motor Company to the U.S. Department of Defense. McNamara excelled in every job along the way: becoming the youngest-ever professor at Harvard Business School, the first non-family president of Ford, and Secretary of Defense under President John F. Kennedy. He achieved these successes by using quantitative techniques he learned at Harvard to drive goal-oriented efficiency. Unfortunately, his tendency to manage by the numbers had dire consequences when he ran the Vietnam War. Many blame McNamara, who relied on incomplete and inaccurate performance measures, for 58,000 American deaths in a war that the United States ultimately lost. Studying the life choices of Robert McNamara will be a cautionary tale for all leaders and students of business.