When teaching leadership, I often share stories about what the best leaders do to help get employees to perform above and beyond expectations. Discussions center on how managers can demonstrate credibility, charisma, inspiration, emotional and social intelligence, intellectual stimulation, and individual consideration. We research the great leaders — in business, sports, religion or politics — to help see effective behaviors in action and use them as role models.

Another way to learn about leadership is to examine the mistakes leaders make and what they have learned from those. At the Smith School of Business, our MBAs recently examined leaders’ ethical lapses that landed them in trouble. The students had plenty of examples. They uncovered leaders from all types of industries who ran into ethical problems, from the world of sports (Michael Vick, Tiger Woods, Jim Tressel) to politics (former Presidents Nixon and Clinton) to business and world leaders (Ken Lay, Jeffrey Skilling, Mark Hurd, Rajat Gupta, Dennis Kozlowski and Martha Stewart).

What interested the students most was how people who have been so incredibly successful got into so much trouble either because of financial problems (lying, cheating, stealing or embezzling) or personal misconduct.

Some leaders who rise up the ranks start believing they are beyond reproach and that the rules don’t really apply to them. Their confidence looks more like arrogance or hubris. They don’t get much-needed critical feedback from others or they don’t listen to it.

Some of them are able to turn things around, but others never do. Those who make a comeback tend to own up to their mistakes by taking responsibility for them, sincerely apologizing, and making restitution. Others continue to deny they did anything wrong or place the blame elsewhere. As leadership experts Jim Kouzes and Barry Posner noted in their book, “Credibility,” trust is central to credibility and once it is gone, it is very difficult to regain.

Another interesting way of learning about leaders is to study the leaders of the past. Recently, I joined our Smith School executive MBA alumni for a trip to the Gettysburg battlefield to learn leadership lessons from the Civil War. As partners with the Gettysburg Foundation, the Smith School often takes executive groups to the site to delve into the lessons of the past. We traced many of their steps on the battlefield, where 51,000 men became casualties (dead, wounded or captured) and the tide of the Civil War turned over those three days in July 1863. In walking the field, we talked about leadership, strategy, team building, communication, decision-making and adaptability. We delved into the personalities of the various leaders — Robert E. Lee, James “Pete” Longstreet, George G. Meade, Joshua Lawrence Chamberlain — to learn what they must have been thinking when they made certain decisions that led to successes or terrible failures and loss of life.

Our alumni were able to see why learning from the past is so valuable for today’s leaders. Mike Nugent, director of national accounts at Becton Dickinson & Co. noted the value in exploring the generals’ backgrounds and personalities. “We were able to understand their strengths and failures as leaders, their derailers, and their conflict management styles. This helped all of us to see how personality factors can really impact decisions made, whether on the battlefield or in a board room.”

To be an effective leader today, it’s critical to learn from the successful leaders of our times. It’s equally important to look at the challenges faced by past leaders. Learning from mistakes — whether ethical lapses or poor judgments — is a reminder that everyone is capable of greatness, yet also capable of making some very bad decisions. To avoid losing credibility as a leader, be aware of your potential strengths and derailers, especially arrogance. Further, always make sure you have at least several trusted colleagues who will be comfortable telling the truth about your flaws. Otherwise, you, too, could end up like so many successful leaders who have fallen from grace .

Joyce E. A. Russell is the director of the Executive Coaching and Leadership Development Program at The University of Maryland’s Robert H. Smith School of Business. She is a licensed Industrial and Organizational Psychologist and has over 25 years of experience coaching executives and consulting on leadership, negotiations, and career management. She can be reached at jrussell@rhsmith.umd.edu.